We've decided to make the event schemas YAML, so we might as well take
advantage of it.
(This conversion was done mostly automatically, except for:
- s/null/"null"/ in m.room.member
- reformat description in m.room.power_levels
As a side effect, I got rid of all of the horrible symlinks and just put
in all of the proper relative paths. Because the horrible symlinks were
horrible.