Pico-8 javascript runtime

This is my quick and dirty reimplementation of the Pico-8 fantasy console

Known issues

• sfx and music do nothing
• sspr spr and map do not draw anything
• GamePads are initalized, but not used (keyboard input preferred)
• btnp doesn't respect auto repeating
• stat/info do nothing currently
• DIR doesn't output in the same format (missing current directory name)
• Audio mixer doesn't have effects, is poorly tuned and is generally broken