Improve readyqueue perf, rapid fire, small improvements

This does the following:

 * Adds very basic rapid fire when holding shift (e.g. hold shift+tab+z.)
 * Adds an atomic check variable around `MoveEvents()`, since they're rare.  I had trouble verifying this improved perf, but @KentuckyCompass's fps counter shows a reproducible improvement of maybe 2%.
 * Moves threadReadyQueue back to a std::vector.  It did show up in profile, after all.  I opted to create a simple wrapper class.
 * Avoids some slow runtime type casts / other minor stuff.

This significantly improves (mostly because of rapid fire, heh) the time it takes to get through the intro of Hexyz Force.  Overall, in game fps improvement by ~5% on Windows release once past the intro.

sceKernelThread.cpp is kinda big, I'm wondering if breaking callbacks and maybe some things out into another file is realistic... I guess it's not hurting anyone, though...

-[Unknown]