This does something that could not be done trivally back when this project
started: concatenate all files, which are written as CommonJS modules. I
had to write custom code to do this with other projects; Browserify was but
an infant back in the day, and I remember SubStack talking about it on
freenode.
Rendering now relies on hooking MapState, which represents the current state of
the map, raising events as various game objects change position or state.
This is a simple proof-of-concept---the tank moves, but only upward, and the
tile redraw does need work. There is no collision detection.