Added - Gravity, Movement Time

- Gravity (if there is an empty tile below current tile, the current
tile will drop down a row)
- Each tile has a movement time, but it's mostly used for the focus tile
so that the player doesn't rapidly speed across the map. (note: add
movement time to gravity events)
Added - Jumping time

Tiles are now given a jump time. This is mostly there to make a
distinction between general movement time, since it's difficult to have
that and gravity cooperate properly.
- Small map changes