* Numerous changes & small bug fixes in PKE sim code and test suite.

* Numerous changes & small bug fixes in PKE sim code and test suite.

  for sim/testsuite/sky:

	* t-pke4.run: Removed test, since it succeeds yet returns a
 	non-zero exit code.

	* Makefile.in (RUNOPTS): Removed --memory-size flag, made
 	unnecessary by sim/mips/interp.c changes.
	(TESTS): Removed t-pke4.ok target.

	* t-pke3.trc: Classified tests with [---] indicators, to match
 	items up with entries documented in testplan.sgml.  Added numerous
 	additional tests.  They assert behavior that assumes certain
 	favorable answers to PKE question set #6 to SCEI.

	* t-pke1.trc: Added some [---] indicators.

  for sim/mips:

	* sky-pke.c (pke_issue): Revamped interrupt & stall code.  Assume
 	that ER1/ER0/PIS bits are only set if not masked by ERR bits.
  	Signal PIS only if unmasked.
	(pke_code_error): Signal ER1 only if unmasked.
	(pke_pc_fifo): Signal ER0 only if unmasked.
	(pke_code_unpack): Round up num_operands for last operand's
 	partial-word.  Factor out "R" bit handling for better coverage
 	analysis.  Fill upper words of a quadword with zeroes for Vn_m
 	UNPACK with n < 4.

	* sky-device.c (device_error): Made function accept varargs.

	* sky-device.h (device_error): Changed declaration to match.

	* interp.c (sim_open): Made 0x0000 area memory be an alias of
	the K0/K1 segments.  Sanitized code.