Debugger: clean up UI.
Debugger: frames use 2-1 split instead of 3 columns.
Debugger: signal node type legend.
Fix whitespace.
Debugger: make Mario.elm less than 50 cols wide so it fits on the projector.
Debugger: generate legend for signal graph.
Debugger: don't show compile errors during hot swapping so it doesn't distract from my live demo.