A simple framework for drawing on screen.
Key features:
* draw directly on the texture
* different pen sizes and colors, easy to configure more
* save/load the texture from Application.persistentDataPath
* works on mobile (tested on Android and iOS)
* full commented source code included
* easy to change to suit your needs
* NEW: clear to a specific color instead of white
* NEW: "stickers" (the ability to draw a texture at specific coordinates on the drawing canvas)
