Update TOC to 50200

- Change PopulateMusic_Windows.js to compare file types instead of file
extensions (which are only included in the name when they're shown in
Windows explorer).
-- Move file type checks into the isAudioFile function to make the logic
easier to change in future.
- Replace all == with === in PM_Windows.js
- Add a missing backslash in the main comment of
ScriptParts\music_part0.lua and music.lua