Merge branch 'master' into viewport

# Conflicts:
#	examples/imgui_impl_dx10.cpp
#	examples/imgui_impl_dx10.h
#	examples/imgui_impl_dx11.cpp
#	examples/imgui_impl_glfw.cpp
#	examples/imgui_impl_glfw.h
#	examples/imgui_impl_opengl2.cpp
#	examples/imgui_impl_opengl2.h
#	examples/imgui_impl_opengl3.cpp
#	examples/imgui_impl_sdl.cpp
#	examples/imgui_impl_sdl.h
#	examples/imgui_impl_vulkan.h
#	examples/imgui_impl_win32.cpp

examples/example_glfw_opengl3/main.cpp

@@ -7,7 +7,8 @@
 #include "imgui_impl_glfw.h"
 #include "imgui_impl_opengl3.h"
 #include <stdio.h>
-#include <GL/gl3w.h>    // This example is using gl3w to access OpenGL functions (because it is small). You may use glew/glad/glLoadGen/etc. whatever already works for you.
+#include <GL/gl3w.h>    // This example is using gl3w to access OpenGL functions. You may freely use any other OpenGL loader such as: glew, glad, glLoadGen, etc.
+//#include <glew.h>
 #include <GLFW/glfw3.h>
 
 static void glfw_error_callback(int error, const char* description)