[M] When jumping into a brick and there is a powerup, it should change direction or not,
depending where the collision was. It currently sucks.
[M] Tux should fall while walking in tiles that have a space between.
+[M] Camera movement shouldn't be so fast at the beggining, it takes the focus from
+ the game.
[L] time runs while being in in-game menu, at least a bit (jump, go to
menu, wait a bit, leave menu, Tux will 'flip' to the ground,
instead of fall, pause mode doesn't seem to have this problem, only
menu)
-[L] Backscroll is really messed up right now :)
[L] change lispreader to throw exceptions instead of simply assert() on
syntax error
[L] fadein/out for intro/extro would be nice