Moved some decls to rt_types.h.  Put legacy UG_INTRO here.  Removed pre-PFIELD decls.
Moved some decls to rt_types.h.  Put legacy UG_INTRO here.  Removed pre-PFIELD decls.

RTcmix/RTcmix,RTcmix/RTcmix,RTcmix/RTcmix,RTcmix/RTcmix,RTcmix/RTcmix,RTcmix/RTcmix