Initial version of libgames-scores

Fake pull request for initial review of libgames-scores.

Hint: scroll down towards the bottom to get to the newer comments.
I know this function works because I know your scores dialog works, but it's past my bedtime and has left me confused.  Why did you write it this way, casting the bools to ints?  A typical comparison function would be `return a.score - b.score;` or vice-versa; that would be more idiomatic and easier for readers.