Merge branch 'master' into docking

# Conflicts:
#	backends/imgui_impl_dx10.cpp
#	backends/imgui_impl_dx10.h
#	backends/imgui_impl_vulkan.h
#	backends/imgui_impl_win32.cpp
#	docs/CHANGELOG.txt
#	examples/README.txt
#	examples/example_glfw_opengl2/main.cpp
#	examples/example_glfw_opengl3/main.cpp
#	examples/example_glfw_vulkan/main.cpp
#	examples/example_sdl_directx11/main.cpp
#	examples/example_sdl_opengl2/main.cpp
#	examples/example_sdl_opengl3/main.cpp
#	examples/example_sdl_vulkan/main.cpp
#	examples/example_win32_directx10/main.cpp
#	examples/example_win32_directx11/main.cpp
#	examples/example_win32_directx12/main.cpp
#	examples/example_win32_directx9/main.cpp
#	imgui.cpp
#	imgui.h
#	imgui_demo.cpp
#	imgui_internal.h

imgui_draw.cpp

@@ -1,4 +1,4 @@
-// dear imgui, v1.79
+// dear imgui, v1.80 WIP
 // (drawing and font code)
 
 /*