Improve documentation for architecture

- Simplify `README.md` by creating and moving some documentation to
`architecture.md`.
- Add more documentation for state handling between layers.
- Improve some documentation to use clearer language.

docs/presentation.md

@@ -1,53 +1,63 @@
 # Presentation layer
 
-- Consists of Vue.js components and other UI-related code.
-- Desktop application is created using [Electron](https://www.electronjs.org/).
-- Event driven as in components simply listens to events from the state and act accordingly.
+Presentation layer consists of UI-related code. It uses Vue.js as JavaScript framework and includes Vue.js components. It also includes [Electron](https://www.electronjs.org/) to provide functionality to desktop application.
+
+It's designed event-driven from bottom to top. It listens user events (from top) and state events (from bottom) to update state or the GUI.
+
+📖 Refer to [architecture.md (Layered Application)](./architecture.md#layered-application) to read more about the layered architecture.
 
 ## Structure
 
 - [`/src/` **`presentation/`**](./../src/presentation/): Contains all presentation related code including Vue and Electron configurations
   - [**`bootstrapping/`**](./../src/presentation/bootstrapping/): Registers Vue global objects including components and plugins.
   - [**`components/`**](./../src/presentation/components/): Contains all Vue components and their helper classes.
-    - [**`Shared/`**](./../src/presentation/components/Shared): Contains Vue components and component helpers that are shared across other components.
-  - [**`assets/`**](./../src/presentation/assets/styles/): Contains assets that will be processed by webpack.
+    - [**`Shared/`**](./../src/presentation/components/Shared): Contains Vue components and component helpers that other components share.
+  - [**`assets/`**](./../src/presentation/assets/styles/): Contains assets that webpack will process.
     - [**`fonts/`**](./../src/presentation/assets/fonts/): Contains fonts
     - [**`styles/`**](./../src/presentation/assets/styles/): Contains shared styles used throughout different components.
-      - [**`components/`**](./../src/presentation/assets/styles/components): Contains styles that are reusable and tightly coupled a Vue/HTML component.
+      - [**`components/`**](./../src/presentation/assets/styles/components): Contains reusable styles coupled to a Vue/HTML component.
       - [**`vendors-extensions/`**](./../src/presentation/assets/styles/third-party-extensions): Contains styles that override third-party components used.
-      - [**`main.scss`**](./../src/presentation/assets/styles/main.scss): Primary Sass file, passes along all other styles, should be the only file used from other components.
+      - [**`main.scss`**](./../src/presentation/assets/styles/main.scss): Primary Sass file, passes along all other styles, should be the single file used from other components.
   - [**`main.ts`**](./../src/presentation/main.ts): Application entry point that mounts and starts Vue application.
   - [**`electron/`**](./../src/presentation/electron/): Electron configuration for the desktop application.
     - [**`main.ts`**](./../src/presentation/main.ts): Main process of Electron, started as first thing when app starts.
-- [**`/public/`**](./../public/): Contains static assets that will directly be copied and not go through webpack.
-- [**`/vue.config.js`**](./../vue.config.js): Global Vue CLI configurations loaded by `@vue/cli-service`
-- [**`/postcss.config.js`**](./../postcss.config.js): PostCSS configurations that are used by Vue CLI internally
-- [**`/babel.config.js`**](./../babel.config.js): Babel configurations for polyfills used by `@vue/cli-plugin-babel`
+- [**`/public/`**](./../public/): Contains static assets that are directly copied and do not go through webpack.
+- [**`/vue.config.js`**](./../vue.config.js): Global Vue CLI configurations loaded by `@vue/cli-service`.
+- [**`/postcss.config.js`**](./../postcss.config.js): PostCSS configurations used by Vue CLI internally.
+- [**`/babel.config.js`**](./../babel.config.js): Babel configurations for polyfills used by `@vue/cli-plugin-babel`.
 
 ## Application data
 
-- Components and should use [ApplicationFactory](./../src/application/ApplicationFactory.ts) singleton to reach the application domain.
-- [Application.ts](../src/domain/Application.ts) domain model is the stateless application representation including
-  - available scripts, collections as defined in [collection files](./collection-files.md)
-  - package information as defined in [`package.json`](./../package.json)
-- 📖 See [Application data | Application layer](./presentation.md#application-data) where application data is parsed and compiled.
+Components (should) use [ApplicationFactory](./../src/application/ApplicationFactory.ts) singleton to reach the application domain to avoid [parsing and compiling](./application.md#parsing-and-compiling) the application again.
+
+[Application.ts](../src/domain/Application.ts) is an immutable domain model that represents application state. It includes:
+
+- available scripts, collections as defined in [collection files](./collection-files.md),
+- package information as defined in [`package.json`](./../package.json).
+
+You can read more about how application layer provides application data to he presentation in [application.md | Application data](./application.md#application-data).
 
 ## Application state
 
-- Stateful components mutate or/and react to state changes in [ApplicationContext](./../src/application/Context/ApplicationContext.ts).
-- Stateless components that does not handle state extends `Vue`
-- Stateful components that depends on the collection state such as user selection, search queries and more extends [`StatefulVue`](./../src/presentation/components/Shared/StatefulVue.ts)
-- The single source of truth is a singleton of the state created and made available to presentation layer by [`StatefulVue`](./../src/presentation/components/Shared/StatefulVue.ts)
-- `StatefulVue` includes abstract `handleCollectionState` that is fired once the component is loaded and also each time [collection](./collection-files.md) is changed.
-- Do not forget to subscribe from events when component is destroyed or if needed [collection](./collection-files.md) is changed.
-  - 💡 `events` in base class [`StatefulVue`](./../src/presentation/components/Shared/StatefulVue.ts) makes lifecycling easier
-- 📖 See [Application state | Application layer](./presentation.md#application-state) where the state is implemented using using state pattern.
+Inheritance of a Vue components marks whether it uses application state . Components that does not handle application state extends `Vue`. Stateful components mutate or/and react to state changes (such as user selection or search queries) in [ApplicationContext](./../src/application/Context/ApplicationContext.ts) extend [`StatefulVue`](./../src/presentation/components/Shared/StatefulVue.ts) class to access the context / state.
+
+[`StatefulVue`](./../src/presentation/components/Shared/StatefulVue.ts) functions include:
+
+- Creating a singleton of the state and makes it available to presentation layer as single source of truth.
+- Providing virtual abstract `handleCollectionState` callback that it calls when
+  - the Vue loads the component,
+  - and also every time when state changes.
+- Providing `events` member to make lifecycling of state subscriptions events easier because it ensures that components unsubscribe from listening to state events when
+  - the component is no longer used (destroyed),
+  - an if [ApplicationContext](./../src/application/Context/ApplicationContext.ts) changes the active [collection](./collection-files.md) to a different one.
+
+📖 Refer to [architecture.md | Application State](./architecture.md#application-state) to get an overview of event handling and [application.md | Application State](./presentation.md#application-state) for deeper look into how the application layer manages state.
 
 ## Modals
 
-- [Dialog.vue](./../src/presentation/components/Shared/Dialog.vue) is a shared component that can be used to show modal windows
-- Simply wrap the content inside of its slot and call `.show()` method on its reference.
-- Example:
+[Dialog.vue](./../src/presentation/components/Shared/Dialog.vue) is a shared component that other components used to show modal windows.
+
+You can use it by wrapping the content inside of its `slot` and call `.show()` function on its reference. For example:
 
   ```html
     <Dialog ref="testDialog">
@@ -58,15 +68,15 @@
 
 ## Sass naming convention
 
-- Use lowercase for variables/functions/mixins e.g.
+- Use lowercase for variables/functions/mixins, e.g.:
   - Variable: `$variable: value;`
   - Function: `@function function() {}`
   - Mixin: `@mixin mixin() {}`
-- Use - for a phrase/compound word e.g.
+- Use - for a phrase/compound word, e.g.:
   - Variable: `$some-variable: value;`
   - Function: `@function some-function() {}`
   - Mixin: `@mixin some-mixin() {}`
-- Grouping and name variables from generic to specific e.g.
+- Grouping and name variables from generic to specific, e.g.:
   - ✅ `$border-blue`, `$border-blue-light`, `$border-blue-lightest`, `$border-red`
   - ❌ `$blue-border`, `$light-blue-border`, `$lightest-blue-border`, `$red-border`