Add "rtsname" token to grpinfo grammar.

source/build/include/common.h

source/build/src/engine.cpp

source/duke3d/src/astub.cpp

source/duke3d/src/cmdline.cpp

source/duke3d/src/common.cpp

source/duke3d/src/common_game.h

source/duke3d/src/game.cpp

source/duke3d/src/game.h

source/duke3d/src/grpscan.cpp

source/duke3d/src/grpscan.h