Add OSX license and readme
Merge pull request #202 from vlag/master

Add OSX license and readme
Survive when sounds and musics required by the engine are not found.
Typo in doc.
Don't die if trying to run a savegame without starting location.
Merge branch 'master' into v1.1
Editor: fix a possible NullPointerException when opening an invalid map.
Basic but working implem of camera stoppers (no scrolling yet). #177