The "paths" option of yuidoc.json was wrong.
The method name in the documentation was wrong.
Another wrong method name.
Specifying that the return type is an array of Canvace.Stage.Entity.
The path field in yuidoc.json is definitely useless for canvace.js.
Adding a new Canvace.Timing module which provides abstraction of the timing APIs provided by the browser.
Removing Canvace.Timing.animationStartTime().

It's better to use Canvace.Timing.now() to measure times, also inside of the requestAnimationFrame() callbacks, since the timestamp passed to the requestAnimationFrame() callback has a higher resolution on some browsers (e.g., latest Chrome uses microseconds instead of milliseconds).
~ Canvace.Timing.
Merge branch '130117-timing' into 130115-physics

Conflicts:
	src/RenderLoop.js
	src/Timing.js