added Jelly Gear test
added updateToll method to input
added Tool as a convenient wrapper for user interaction
call current Tool in main loop
added convenient methods to ToolEvent
use a tool to enable dragging on bodies
added absolute function in Jello.Vector2
added key up and down callback functionality
added second tool to create jelly cubes
have to explicitly add a Ray to World
added additional button listeners
added removeRay method to World
add and remove Ray via a Tool
control direction of Tool Ray via mouseDrag event