Merge branch 'master' into docking (incl merge moved CurrentDpiScale field)

# Conflicts:
#	backends/imgui_impl_osx.mm
#	backends/imgui_impl_win32.cpp
#	imgui.cpp

backends/imgui_impl_glut.cpp

@@ -167,6 +167,7 @@ static ImGuiKey ImGui_ImplGLUT_KeyToImGuiKey(int key)
 bool ImGui_ImplGLUT_Init()
 {
     ImGuiIO& io = ImGui::GetIO();
+    IMGUI_CHECKVERSION();
 
 #ifdef FREEGLUT
     io.BackendPlatformName = "imgui_impl_glut (freeglut)";