[commit] misc cleanup / tweaks

[Doug Evans]

Hi.

fyi,
I checked this in.

	* sim.scm (/operand-number-elaboration-written?): New variable.
	(/op-gen-written-update op): New function.
	(/op-gen-set-trace, /op-gen-set-trace-parallel): Call it.

	* read.scm (/cmd-define-rtl-version): Only log rtl version if changed.

	* operand.scm (op-nub): Delete.

	* dev-utils.scm: New file.
	* dev.scm (srcdir, load-doc, load-opc, load-gtest, load-sid,
	load-sim, load-stest, load-testsuite): Moved to dev-utils.scm.
	* read.scm (CHECK-LOADED?, libcpu.so, /loaded-file-list, /loaded-file?,
	/loaded-file-record!, maybe-load): Delete.
	Load cgen files directly instead of via maybe-load.