* Monster bug fixes & improvements from the last two days' demo-testing work.

* Monster bug fixes & improvements from the last two days' demo-testing work.

	* sky-pke.h (pke_fifo*): Exported these formerly private functions.
	(pke_device): Added FIFO cache fields.

	* sky-pke.c (pke_fifo_reset): New function for GPUIF client -
 	clear FIFO contents.
	(pke_pcrel_fifo): Added caching facility to prevent O(n^2) cost for
	searching for consecutive operand words.

	* sky-libvpe.c (MEM, uMEM): New/changed macros that perform modulo
 	calculations to handle out-of-range VU memory addresses.
	(*): Replaced many previous uses of MEM[] and state->uMEM[] with
	calls to above macros.

	* sky-vu.h (struct VectorUnitState): Added qw/dw size fields for
	MEM/uMEM buffers, for overflow prevention.  Renamed MEM/uMEM fields
	to catch all their prior users.

	* sky-vu0.c (vu0_attach): Manually align MEM0/MEM1 buffers to force
	16-byte alignment.  (zalloc is not enough.)

	* sky-vu1.c (vu1_attach): Ditto.
	(init_vu): Store buffer sizes from allocation into VectorUnitState.

	* sky-gpuif.h (GifPath): Use a pke_fifo strucf instead of
 	temporary fixed-size array for flexible FIFO sizing.

	* sky-gpuif.c (SKY_GPU2_REFRESH): This is now an integer value to be
	used as a modulus for periodic refresh.
	(refresh): New function to send GPU2 refresh code periodically.
	(*): Use pke_fifo calls to en/dequeue GPUIF tags & operands.

	* sky-pke.h (struct pke_device): Added fields to allow caching of
 	results from recent FIFO searches.