This commit:
- Fixes broken URLs using archive.org or other references.
- Replaces tenforums.com URLs with better documentation as they tend to return HTTP status code 403 to tests and also are low quality source.
- Changes all insecure http sources to https alternatives
- Adds integration tests to check for broken URLs
- There's logic implemented for having a delay inbetween when sending requests to same domains, however it's not used as the sources can respond to totally parallelized requests.
- Run test pipeline weekly to get notified about broken URls without commits
Integration tests are executed using vue-cli-service with double quotes as following: `vue-cli-service test:unit "tests/integration/**/*.spec.ts"`. Using single quotes (mochajs/mocha#1828) works on macOS and Ubuntu but does not on Windows (tests are not found). Double quotes is the only portable way that works on all three platforms (mochajs/mocha#3136).
