v0.1.3 rewrite
v0.1.3 rewrite

Put the whole functionality in an object.  
Rewrote some functions to be more clear.  
Rewrote canvas.draw function to draw in the center of the canvas.  
Adds an option to keep previous circles.  
Adds a button to clear the canvas and cache of previous circles.  
CytoDev/PixelCircleGenerator,CytoDev/PixelCircleGenerator