Simplification of updates and initial installation

[15532th]

Original repo name uses dashes instead of underscores, making it non-trivial to import from a filesystem, and gets around it by requiring installation. Since this fork depends on its own version of youtube-community-tab library, it is necessarily to repeat installation as part of update process. It seems like unnecessarily hassle to me, and I have seen at least one user having difficulties updating.

As a way to simplify updating I suggest creating in top level directory of the fork symlink youtube_community_tab pointing to youtube-community-tab/src/youtube_community_tab. This way ytct.py will be able to import it directly from filesystem, eliminating need to install. Update process would become a simple git pull or "re-download it from github", which seems to be easier for inexperienced users.

As for initial installation, since project only has a single dependency, it could be placed in requirements.txt in top level directory, giving it better visibility and making it easier to change if a need arises in the future.

[15532th]

Apparently making cross-platform links is not as simple as it seemed to be.
Commiting with git config core.symlinks set to true makes symlink work correctly on Windows when repo is retrieved with git clone, but downloading and unpacking zip-file still makes it a plain text file, so imports doesn't work correctly.

The only alternative solution not involving renaming directories of original repo I see is to use importlib to import module directly from youtube-community-tab/src/youtube_community_tab.