Merge branch 'viewport' into docking ...

# Conflicts:
#	examples/example_glfw_opengl2/main.cpp
#	examples/example_glfw_opengl3/main.cpp
#	examples/example_glfw_vulkan/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

Viewport: GLFW: Build fix for pre GLFW 3.2 (#1542)

Viewport: Enabled viewports by default in more example apps.

Merge branch 'viewport' into docking ...

# Conflicts:
#	docs/CHANGELOG.txt
#	imgui_demo.cpp
#	imgui_internal.h

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.

Internals: Replace unsigned short with ImWchar when dealing with character storage (missing cases) + in imgui_impl_ file keep using neutral type everywhere, added missing explicit cast in three bindings. (#2078)

Merge branch 'master' into viewport ...

# Conflicts:
#	imgui.cpp
#	imgui_internal.h

Docking: io.ConfigResizeWindowsFromEdges default to true in Docking branch. Moved code in BeginTabItem().

example_glfw_vulkan was missing a reference to imgui_widgets.cpp (#2071, #2036)

Merge branch 'docking2' into viewport_docking ...

# Conflicts:
#	examples/example_glfw_opengl2/main.cpp
#	examples/example_glfw_opengl3/main.cpp
#	examples/example_glfw_vulkan/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
#	imgui.cpp
#	imgui.h
#	imgui_demo.cpp
#	imgui_internal.h

Examples: Enabled Docking + Nav by default in the branch. (#351)

Merge branch 'master' into viewport

Examples: imgui_impl_opengl3 Fix GLAD error condition (#2059, #2002) ...

`gladLoadGL` returns 0 on fail, not the other way around.

Merge branch 'master' into viewport ...

# Conflicts:
#	imgui.cpp

Comments, readme updates

OSX: Added imgui_widgets.cpp to xcode project files.

Refactor: Added empty imgui_widgets.cpp + updated project files / makefiles etc. accordingly (#2036)

Refactor: Added empty imgui_widgets.cpp + updated project files / makefiles etc. accordingly (#2036)

Merge branch 'master' into viewport ...

# Conflicts:
#	examples/example_glfw_opengl3/main.cpp
#	examples/imgui_impl_opengl3.cpp
#	imgui.cpp
#	imgui_internal.h

Examples: Vulkan: Minor tweaks.

Examples: OpenGL: Added support for glew and glad OpenGL loaders out of the box. (#2001, #2002). Changelog, tweaks, applied changes to SDL+OpenGL3 example.

WIP on configurable OpenGL loader. (#2001, #2002)

Examples: Vulkan: Viewport: Tweak to improve framerate on multiple-viewport situations, tho it is still halving the unthrottled framerate on nvidia for some reason.. Followup to 4dea032 (#1542)

Merge branch 'master' into viewport ...

# Conflicts:
#	imgui.cpp
#	imgui.h

Examples: Vulkan: Fixed handling of VkSurfaceCapabilitiesKHR::maxImageCount = 0 case. Tweaked present mode selections.

Examples: Viewport: Disabling swap intervals / vsync on secondary context to match what the DX11 bindings is doing. (#1542)

Merge branch 'master' into viewport ...

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

Examples: imgui_impl_vulkan: Comments (re)

Examples: imgui_impl_vulkan: Comments