Refactored and simplified behaviours

gJump is gone, replaced with jump, approx 60 lines replaced with about
5! sMove is unused and removed, equivalent will be much easier to
implement now. Want to add "onGround" function, test as True before
allowing jump or moveForward. Also want to increase gravity for player
(actually, screw it, globally) and counter with higher/faster jump,
replace magic numbers for player movement speed with variables etc.