Making groups for discussions

[cadop]

It would be nice to be able to add one more layer of categories that are controlled by the admin, so we can group discussions. I think this would be a really nice combination, and allow user flexibility to setup their repository as a mix between an actual discussion board and the StackOverflow style that is currently implemented.

Something like:

This way, if there is a repo that has some Python API and C API (or backend), we can have a separate discussion board, keeping the nice categories that come default (like the ability to have it tagged/sorted by Answerable questions, feedback, sharing).