Different modes and level improvements

Hi,

I added several game modes to the game.  

Normal mode is the standard game mode as it is already in the game, no life limit and normal speed.  

Hard mode means you start with 5 lives and when the lives are used then the game is over.  

Speed Mode means the game runs faster than normal for those who find it is too slow.  

Super Speed means the game is much faster and only playable for genetically optimized humans or aliens.

In the first level I changed the tree trunk on the river so that it only starts swimming when the player enters the trunk.