Beta update 10

Added support for docs in the game.json file using Markdeep, Markdown, HTML, and text format. Good for game design docs, TODO lists, and game manuals
Added support for Ctrl+G as an alternative GIF recording keystroke
Renamed signNonZero() to signNotZero() to match the manual
Added MIN() and MAX() intrinsics
Fixed opacity == 0 on drawSprite() to draw nothing instead of full opacity
Added rndBall() and rndSphere()
Changed sprite.json name for a single xy() to be a sprite instead of an animation