Merge branch 'master' into docking

# Conflicts:
#	backends/imgui_impl_glfw.cpp
#	imgui.cpp

backends/imgui_impl_vulkan.h

@@ -149,7 +149,7 @@ struct ImGui_ImplVulkanH_Window
     ImGui_ImplVulkanH_Window()
     {
         memset((void*)this, 0, sizeof(*this));
-        PresentMode = VK_PRESENT_MODE_MAX_ENUM_KHR;
+        PresentMode = (VkPresentModeKHR)~0;     // Ensure we get an error if user doesn't set this.
         ClearEnable = true;
     }
 };