Fix encoding of comments.

This makes some files use utf-8 and fixes a weird quote in another comment.
Apply whitespace fix to SDL2 branch.
Only call onMusicOver if the music naturally ends.

We were playing the bg music over the cutscene music.

This stops us from calling onMusicOver when we call Mix_HaltMusic. This is a
regression after upgrading to the latest SDL_mixer, due to a change in
functionality. (https://bugzilla.libsdl.org/show_bug.cgi?id=1610)

Fixes GH-129.