Update .gitignore; complete MyAnimeList

- Fixed .gitignore to properly ignore all pycache and files directories.
  Files' directory reserved for the end user's storage of episode data.

- Updated MyAnimeList class. The end user can now choose MyAnimeList and
  provide their username to download a text file with anime series that
  they are currently watching.

- Moved array of compatible websites to its own module to be imported. The
  list may grow over time and importing the list will prevent overcrowding
  the main function.