KNOWN BUGS

- when the tileset is loaded twice, the tiles are black. Fix it!

- sometimes there are font problems. Take the new font from paragui 1.0.4.
    Update: Propably a rare bug in the combination paragui/libfreetype

BUGS TO BE VERYFIED

- when you exit at the correct time, the bigmap timer will be raised, leading
to a segfault
    Update: When destroying bigmap, I have inserted a sleep. Is not the perfect
    solution, but should prevent the race condition. Besides, the blitting done
    by the bigmap should consume a lot less time now.

- the game occasionally crashes on exit
    Update: looks like this has gone, but I don't really now why.
