Adding color property to NGon

To allow for fun colored balls
First stab at Stroke vs Stroke geometry hit tests

Adding static method strokeCollideTest to attempt Stroke vs Stroke
collide tests. It is useful for some things, but will rapidly get very
slow in its current form. But it is a start
Adding Collision Example

This example demonstrates how to perform geometry based hit tests,
through Touch events (mouse movement) and Stroke vs Stroke collision
detection. The Stroke vs Stroke test will get slow with long strokes,
currently, but it will improve in the future :)