Rail Map

[DasCapschen]

This adds a map to the game. See #76.

Press "M" to open the overlay map, which shows only the current route, player position and station names.
It is always zoomed out fully.

Press "M" again to show the fullscreen map, which shows all rails on the map, the players position, station names and signals.
Player can use the mouse wheel to zoom in and out. Player can also click and hold middle mouse button and drag to move the view around. Pressing "Space" will center the map on the player and follow the player.

Press "M" a third time to close the map.

Changes to existing code:

• added setgetand signals in Signal.gd to update the map when signals change
• added a signal in World.gd when a big chunk updates the world origin translation
• added get_global_transform_at_rail_distance(distance) in Rail.gd

Here is a sample of the overview map:

Here is a sample of the fullscreen map: