added pause/resume to actions.
Add accessor for done in JGAction
Added support for JGAction done/paused in game loop.
Moved concept of an action with a duration into the JGDurationAction class.
Added concept of being/end functions for actions.
Updated JGMoveTo to use the JGActionDuration base class.
Added a JGActionChain class for chaining actions.
Added exampel of an action chain in example scene.