VMM: Added a bMainExecutionEngine member to the VM structure for use instead of fHMEnabled and fNEMEnabled. Changed a lot of HMIsEnabled invocations to use the new macros VM_IS_RAW_MODE_ENABLED and VM_IS_HM_OR_NEM_ENABLED. Eliminated fHMEnabledFixed. Fixed inverted test for raw-mode debug register sanity checking. Some other minor cleanups.