GameFeel week 1

Changes:

1. Added coyote time (player can jump shortly after walking of a ledge)
2. Changed the way jump height is calculated to make the jump smoother, instead of the cut-off that happened when the user let go of the spacebar.
3. Changed walking speed build-up so that it instantly gets to the max walking speed, instead of the slow build-up it was before. When the player stops walking, the walking speed will slowly decrease until the player stands still. 
4. The player can instantly move in another direction if input is given that way, unless the player is in the air.