Oy...
Implemented a startup hook in CaelumEngine. This way, the game threads will all be running near simultaneously.
Delegated 4 IGame methods over to a new interface, plus 2 new ones.
Implemented IThreadable, as well as a wrapper for it via ThreadTimedWrapper.
IUpdatable.update() now includes a boolean for whether the X is paused. I'll probably delegate it over to an interface or something.
Removed a good hunk of the code in ThreadGameLoop, in favor of using ThreadTimedWrapper.
Removed ThreadStoppable's constructor that accepted an instance of Runnable. What was I thinking?
ThreadTimed now requires you to call super.initiate().
Two things:
Idiot (or genius, depending on your POV)-proofed the initiated flag in ThreadTimed.
Removed the instanceof checks in ThreadTimedWrapper. If you want to do X, you can do X.*

* Just don't come crying to me when X blows up in your face, or makes you work harder.
One more thing: I fixed a bug that caused the update count in ThreadTimed to not get reset like it's supposed to.
Fixed the delta calculation in ThreadTimed.