SelectMgr → MMgt Relation

File in src/SelectMgr	Includes file in src/MMgt
SelectMgr_Filter.hxx	MMgt_TShared.hxx
SelectMgr_Selection.hxx	MMgt_TShared.hxx
SelectMgr_SelectionManager.hxx	MMgt_TShared.hxx
SelectMgr_ViewerSelector.hxx	MMgt_TShared.hxx