Moved rendering functionality in ploma.js to have it available as a plugin

created Ploma module object in ploma.js and moved initialization to init.js. Ploma encapsulates Sketcher prototypes - to create an object that renders stroke arrays, create a Ploma.Sketcher instance with parameters canvas, textureCanvas1 and textureCanvas2. A sketcher instance provides and interface with addPoint, beginStroke and finishStroke and has public values strokes (Array) and curStroke, both the filtered version of points/strokes.
I have changed both of these `this.strokes` and `this.curStroke` to functions that return arrays (or 2D arrays) of plain JS obj's with x/y/p data instead of the `Point` objects they were returning because `Point` is internal to Ploma now.