updated references to rigidbody 2d
just set it to enum to allow dropdown select in inspector
Merge branch 'develop' into feature/enemy-death
fixed spacing
renamed enemy prefab to Enemy, added values for powerup
chose "SpeedPowerUp" for power up type on SpeedPowerUp prefab
added speed (and default) and localtransform reference
move powerups slowly to the right
add power up type to player inventory when collected
drop power up method added, currently drops only speed powerup