Known bugs:
* The Pixel format in the Grid has DX and DY attributes and
it wreaks havoc on collision detection in Play Mode when you
come straight from the editor. Reloading the map from disk to
play is OK cuz it lacks these attrs.
Implements the dev console in-game with various commands to start out
with.
Press the Enter key to show or hide the console. Commands supported:
new
Start a new map in Edit Mode.
save [filename.json]
Save the current map to disk. Filename is required unless you
have saved recently.
edit filename.json
Open a map from disk in Edit Mode.
play filename.json
Play a map from disk in Play Mode.
