Set version to 9100; Remove unused save logic

Removed some logic for dealing with old (ancient, even) saves.
Use string.h only

If strings.h winds up being needed for some platforms, it can be included
through platform-specific defines (e.g. #ifdef WIN32).
Update in-game instructions for reporting bugs
Remove conditionals from global initializations

Also cleaned up several ifdefs that weren't needed or looked better after
rearranging, and added some comments.