Implement drawPoly, drawCircle, and drawElipse in webgl

[KilledByAPixel]

Right now we have these functions but they only draw to the 2d canvas. It shouldn't be too tough to write a polygon rendering system for webgl that uses a different shader then the sprite rendering system. The same system could be used for polys and circles.

LittleJS/src/engineDraw.js

Line 315 in c9930ce

function drawPoly(points, color=new Color, lineWidth=0, lineColor=new Color(0,0,0), screenSpace, context=mainContext)