Side collisions & multiple platform Collisions

- the player can now collide with multiple platforms
- side collisions are working, but incomplete. Currently only collisions
from the left work, and there is a glitch due to how the controls work,
with button up and button down. Also the values for x placement on
collision may need to be adjusted.
-more work on collision_response()  still to be done to make collisions
sensitive to all situations.