Merge branch 'master' into docking

# Conflicts:
#	docs/CHANGELOG.txt
#	examples/example_win32_directx11/main.cpp
#	examples/example_win32_directx9/main.cpp
#	examples/imgui_impl_win32.cpp
#	examples/imgui_impl_win32.h
#	imgui.cpp

examples/imgui_impl_sdl.cpp

@@ -257,6 +257,11 @@ bool ImGui_ImplSDL2_InitForD3D(SDL_Window* window)
     return ImGui_ImplSDL2_Init(window, NULL);
 }
 
+bool ImGui_ImplSDL2_InitForMetal(SDL_Window* window)
+{
+    return ImGui_ImplSDL2_Init(window);
+}
+
 void ImGui_ImplSDL2_Shutdown()
 {
     ImGui_ImplSDL2_ShutdownPlatformInterface();