Merge branch 'master' into viewport ...

# Conflicts:
#	examples/imgui_impl_dx9.cpp
#	examples/imgui_impl_opengl2.cpp
#	examples/imgui_impl_opengl3.cpp
#	examples/imgui_impl_vulkan.cpp

Examples: Using "dear imgui" terminology in all examples headers/comments + fix minor typo.

Merge branch 'master' into viewport ...

# Conflicts:
#	imgui.cpp

Examples: Comments, bits of documentation

Merge branch 'master' into viewport ...

# Conflicts:
#	examples/imgui_impl_glfw.cpp
#	examples/imgui_impl_glfw.h
#	examples/imgui_impl_sdl.cpp
#	examples/imgui_impl_sdl.h
#	examples/imgui_impl_win32.cpp
#	examples/imgui_impl_win32.h
#	imgui.cpp
#	imgui_internal.h

Examples: Comments to clarify how the keyboard data is indexed.

Merge branch 'master' into viewport ...

# Conflicts:
#	examples/imgui_impl_glfw.cpp
#	examples/imgui_impl_win32.cpp

Examples: The functions in imgui_impl_xxx.cpp are prefixed with IMGUI_IMPL_API (which defaults to IMGUI_API) to facilitate some uses. (#1888) + Comments in imgui.h

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: Comments to make ImGuiConfigFlags_NoMouseCursorChange more visible (#1027). + Allegro5: Added support for ImGuiConfigFlags_NoMouseCursorChange flag.

Merge branch 'master' into viewport ...

# Conflicts:
#	examples/imgui_impl_sdl.cpp

Examples: Renamed imgui_impl_sdl2.cpp to imgui_impl_sdl.cpp (#1870) + changelog bits