move createBasicWorkspaceDef to a virtual method so Sample_Compositor and others can override that
move createBasicWorkspaceDef to a virtual method so Sample_Compositor and others can override that

--HG--
branch : v2-0-samples-compositor

digimatic/ogre,digimatic/ogre,digimatic/ogre,digimatic/ogre,digimatic/ogre,digimatic/ogre,digimatic/ogre