Merge branch 'master' into viewport ...

# Conflicts:
#	imgui.cpp

Examples: SDL2+Vulkan: Fixed application shutdown which could deadlock on Linux + Xorg. (#2181)

Examples: OpenGL3: More explicit testing for == GL_UPPER_LEFT in case glGetIntegerv(GL_CLIP_ORIGIN is not honored properly. (#2186, #2195) Fix f52f0a5

Merge branch 'master' into viewport + comments ...

# Conflicts:
#	examples/imgui_impl_opengl3.cpp
#	imgui.cpp

Examples: OpenGL3: Added support for GL 4.5's glClipControl(GL_UPPER_LEFT). (#2186)

Merge branch 'master' into viewport + specific changes for GLFW callbacks ...

# Conflicts:
#	examples/example_glfw_opengl3/main.cpp
#	examples/example_win32_directx11/main.cpp
#	examples/example_win32_directx9/main.cpp
#	examples/imgui_impl_glfw.cpp

Examples: GLFW: User previously installed GLFW callbacks are now saved and chain-called by the default callbacks. (#1759)

Examples: Misc comments mainly related to GLFW callbacks. (#1759)

Examples: OpenGL3+GLFW/SDL: Made main.cpp compile with IMGUI_IMPL_OPENGL_LOADER_CUSTOM (may be missing init). (#2178)

Examples: SDL: Tweaked Windows instructions and batch files. (#2175)

Viewport: Fixed SDL+OpenGL2 example to work with multi-viewports. (#2175)

Examples: SDL: Tweaked Windows instructions and batch files. (#2175)

Examples: Win32: Handle UTf-8 in platform window title setting. (#2164)

Merge branch 'master' into viewport

Examples: GLFW: VS2015 project link with legacy_stdio_definitions.lib in order to link with the precompiled VS2010 GLFW3.lib we provide. (#2010, #2043, #2091)

Examples: Add missing include guards (#2166)

Examples: Vulkan: Avoid unreferenced parameter warning. (#2162)

gladLoadGL() return 0 to indicate failure (#2157)

Merge branch 'master' into viewport ...

# Conflicts:
#	imgui.cpp

Comments in demo and opengl code + Internals: Added HoveredIdNotActiveTimer tracking hovering time unless the item is active, which is a commonly useful pattern.

Merge branch 'master' into viewport ...

# Conflicts:
#	imgui.cpp
#	imgui.h

Examples: SDL: Fixed usage of SDL_GetDisplayDPI (#2137, #1676)

Examples: Downgraded Xcode project object version (50->48) to support Xcode 9.2 (last version supported on macOS 10.12) (#2133, #1929)

Examples: Downgraded Xcode project object version (50->48) to support Xcode 9.2 (last version supported on macOS 10.12) (#2133)

Merge branch 'master' into viewport ...

# Conflicts:
#	examples/imgui_impl_sdl.cpp
#	imgui.cpp

Examples: OpenGL3: Cast compile/link status to GLboolean (#2112, #2125) ...

Some OpenGL loaders/bindings do not allow comparisons between GLints and GLbooleans.

Examples: imgui_imp_opengl3.cpp explicit casting for overly aggressive glbinding compatibility. (#2112) [@hesiod]

Examples: DirectX10, DirectX11: Removed seemingly unnecessary calls to invalidate and recreate device objects in the WM_SIZE handler. (#2088)

Fix spacing in imgui_imp_sdl example (#2111)

Merge branch 'master' into viewport ...

# Conflicts:
#	examples/imgui_impl_win32.cpp
#	examples/imgui_impl_win32.h
#	imgui.cpp