Merge branch 'master' into viewport

# Conflicts:
#	examples/imgui_impl_dx9.cpp
#	imgui.cpp
#	imgui.h

examples/opengl2_example/main.cpp

@@ -27,7 +27,8 @@ int main(int, char**)
     glfwMakeContextCurrent(window);
     glfwSwapInterval(1); // Enable vsync
 
-    // Setup ImGui binding
+    // Setup Dear ImGui binding
+    IMGUI_CHECKVERSION();
     ImGui::CreateContext();
     ImGuiIO& io = ImGui::GetIO(); (void)io;
     io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable;