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.
Hm, is there any reason we can't get rid of the inner `Sketcher` object and just do : `var ploma1 = new Ploma(canvas);` ? (if I embed textures)