[librender] small improvements

src/libRender/CMakeLists.txt

src/libRender/RadiumNBR/Gui/NodeEditor/src/FlowScene.cpp

src/libRender/RadiumNBR/Gui/NodeEditor/src/Node.cpp

src/libRender/RadiumNBR/Gui/NodeGraphControllerGui.cpp

.../RadiumNBR/Gui/RenderGraphEditor/ConnectionStatusData.hpp

src/libRender/RadiumNBR/NodeBasedRenderer.cpp

src/libRender/RadiumNBR/NodeGraph/RenderGraph.cpp

src/libRender/RadiumNBR/NodeGraph/RenderGraph.hpp