Apt-select

- Fix BeautifulSoup Default Parser Type Format

- Latency tests and Launchpad data scraping now work in parallel using threads
- Multiple bug fixes
- Code improvements, using more classes and smaller methods

- Fix bug causing `--top-number` argument to be unsatisfied with mirrors restricted to meet `--min-status` argument or fresher.
- Fix bug that caused endless loop or index error when specifying `--top-number` argument that exceeds the number of successfully tested mirrors.
- Handle SSL read errors when reading Launchpad archive mirror pages.

Initial release (quite unstable).