[MMc] Coins

Gamepads now work for selecting characters and navigating the world map.  In game, there are coins that players can collect:

The coins play a satisfying Mario-like effect due to cfxr.  The command:

   grep ";" *.js | wc -l

reports 1566 source lines of code for Castles & Catacombs. The program clocks in at 8 MB of data and 47 MB of .PSD files that are not used at runtime.

We're debating whether the regeneration attribute should just heal the character who has it, or let that character heal others nearby.  Healing others makes the player feel more valuable to the team, but also could make the player feel like a walking med-kit (I'm sick of playing clerics and medics because of this).

Next:

1. Refactor the scene-loading code to note pointers between scenes.
2. Count coins on load and show the total for the scene (traversing the entire reachable graph)
3. Show the total number of coins on the level
4. Reset scenes (and all child scenes) on leaving them