- elimination of the last remaining real Singleton Object (SimpleFloors):
- attribute/value can now be used on every Object
- max memory increase measured of 1.5 MB on 100x150 Sierpinski Level
- the BorderStone that is not part of the level remains a Singleton Object
- fix bug #7084 stay invisible after it-cherry
- fix bug #7171 check SDL_ttf version (besides cross compile)