Add "totalElapsed" as a parameter to the Ticker's tick events

Currently, tick events only have 2 parameters: "elapsedTime" (aka delta) and a "paused" flag.  
I think it would be great to also have "totalElapsed" and "runTimeElapsed" as additional parameters.

This will allow many of my looping animations to be based off this value, instead of having to maintain their own internal state.