Add the option to synchronize output.

There is potentially one situation where the output bitmap of multiple sprites will be the same:
when their settings are identical, and the currently displayed frame currently matches the one in the settings.
Then in theory their behavior would be practically identical.

In truth the animation of multiple sprites with the same settings MIGHT normally still have a slight offset in actual timing, but in most cases that's neglegable and not important.
But there might be one situation where it might be important:
	Quickly switching between poses with manual "wait" commands in order to hack-together a unique animation...
	... but this mostly involves non-animated poses, or transitioning from animated to non-animated, or vice-versa.
	so it might not matter.

Also, be very careful to ensure that end-frame events still fire.
But that's simply a matter of hiding the individual output-bitmap, and displaying the cache bitmap instead.
The original behavior of updating the individual output can still occur, but that output is hidden, allowing most of the performance boost to exist.
