Hotfix - Platform movement

This is a small hotfix change which fixes platform movement (shown in "devmode 2" as PLTZ) being completely dropped and ignored for players.

Instead, if the platform is moving in the same direction as the player's jump, its velocity will be added to the player's jump speed, allowing them to jump in situations where they previously could not (fast-moving elevators going up). This change explicitly does not dampen the movement of players leaving an elevator going "down", so you will always get at least your full jump height off of the floor.

Moving platforms (such as those in the water-raising room in CEZ2) should no longer be a murderous frustration to jump across with this fix applied, since the player will always jump as high as they expect to jump when they press the jump button.