various changes

-commented out gravity function - acts funny with very thick platforms
-clamped maximum horizontal velocity to 10 - not a perfect workaround;
will think of something better
-made groundcheck radius smaller - no longer able to jump infinitely
when touching 90 degree walls
-added linear drag so that player does not fall at a million miles per
hour (unrealistic man)
-added bottom collider with friction - no more skating sorry
-bottom collider is smaller width than main body to prevent     sticking
to walls
-beginning work on "scythe" enemy; walking animation implemented (see
scene 1)
-beginning work on scene 11