Added support code to enable and disable SVS.  SVS cli command modified to handle those optoins.  SVS object keeps track of whether enabled.  Added is_enabled and set_enabled to svs interface class.  No processing kernel yet affected by this setting.
Added commands to turn SVS on and off.  (svs --enable|-e|--on|--disable|-d|--off]
- Currently on by default, but will be off in release
- SVS maintains enabled state.
- cli_svs.cpp processes those parameters and toggle SVS state, not svs->do_cli_command.
- SVS still gets initialized on agent creation
- SVS still gets informed of state creation and deletion to maintain it's own data structures pertaining to them.  So, svs still creates SVS links when off (epmem and smem do too).
- When off, SVS does not do any processing during the decision cycle other than if a state gets created/deleted.
Merge branch 'soar-9.4' of git@github.com:SoarGroup/soar.git into soar-9.4.  Merges in Aarons addition of SVSQuery.

Conflicts:
	Core/KernelSML/src/sml_KernelSMLHandlers.cpp