map-layer: Reduce tile requests during animations
When the map layer detects that the camera is moving quickly (during an animation, or for some other reason), it will skip requesting tiles on that frame. This helps prevent tiles from being requested if they will likely be discarded before they load.
A recalculate_grid() call is scheduled for the next frame, so if the motion suddenly stops, the tiles will still be loaded.
Fixes #61 (closed)
Edited by Marcus Lundblad