ran cppcheck and fixed some warnings
DrawModes constructor is now explicit which causes some changes: e.g. if you used ACG::SceneGraph::DrawModes::TEXCOORD_PER_VERTEX you now have to use ACG::SceneGraph::DrawModes::DrawMode(ACG::SceneGraph::DrawModes::TEXCOORD_PER_VERTEX)
I am not shure if you want these changes, made them to fix cppCheck warnings. Note that this MR is targeting featureGlutPrimitives branch.