TerraX support for grouping

proj/terrax/vs2013/terrax.vcxproj

proj/terrax/vs2013/terrax.vcxproj.filters

source/terrax/CommandBuildModel.cpp

source/terrax/CommandDuplicate.cpp

source/terrax/CommandGroup.cpp

source/terrax/CommandGroup.h

source/terrax/CommandPaste.cpp

source/terrax/CommandPaste.h

source/terrax/CommandUngroup.cpp

source/terrax/CommandUngroup.h

source/terrax/GroupObject.cpp

source/terrax/GroupObject.h

source/terrax/ProxyObject.cpp

source/terrax/SceneTreeWindow.cpp

source/terrax/SceneTreeWindow.h

source/terrax/UndoManager.cpp

source/terrax/mainWindow.cpp

source/terrax/resource.h

source/terrax/resource/toolbar1.bmp

source/terrax/resource/toolbar2.bmp