Filled Circle brush is just like the Circle brush, but filled. Issue is, when drawing while moving the mouse, some pixels remain unfilled.
Also added some more file brushes.
They're like File brushes, but each time you draw, expect to see something different!
To make a random brush, just put the images you want in the same folder (under the main Brushes folder of course), and make sure their filename starts with "%".
I also changed _process() to _input() in Canvas.gd, so there may be some unexpected behavior.
