Testing the mid-air dash

Testing the mid-air dash as a solution to unfair impossible deaths.
Player can now do a very small second jump in mid-air, and can do it
again if it gets hit by a fireball. This means it can start moving
forward in the air after a knockback, which gives the player control
over where he lands. My thoughts: solves the problem well but might not
be thematic. Not sure if dash should be allowed before being hit at all.
LevelControl as a state

This is an experiment. I think this is much closer to how jMonkey's
"standard" would have it. The entire code would need much work before
fulfilling those standards, however, so maybe it's not worth it.
Changed LevelControl to an AppState

LevelControl is replaced by LevelGeneratingState.