Refactor: Moved InputText functions from imgui.cpp to imgui_widgets.cpp (#2036)

Refactor: Moved ColorEdit/ColorPicker/ColorButton/etc. functions from imgui.cpp to imgui_widgets.cpp (#2036)

Refactor: Moved Tree/Selectable functions from imgui.cpp to imgui_widgets.cpp (#2036)

Refactor: Moved Plot/Value functions from imgui.cpp to imgui_widgets.cpp (#2036)

Refactor: Moved Menu functions from imgui.cpp to imgui_widgets.cpp (#2036)

Refactor: Moved Combo/ListBox functions from imgui.cpp to imgui_widgets.cpp (#2036)

Refactor: Moved Button/Image/Checkbox/RadioButton/Bullet/ProgressBar functions from imgui.cpp to imgui_widgets.cpp (#2036)

Refactor: Moved Text functions from imgui.cpp to imgui_widgets.cpp (#2036)

Refactor: Added imgui_widgets.cpp headers to easily merge in the functions in all our branches. (#2036)

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

Version 1.64 WIP

Merge branch 'master' into viewport ...

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

Changelog tweaks/typos

Version 1.63

Changelog: fixed inconsistent white space before list items.

Internals: Tidying up, moving helpers to imgui_internal.h (in prevision of 1.64 refactor)

Reordered some declarations in imgui.h (in prevision of 1.64 refactor)

ColorEdit4: Fixed a bug when text input or drag and drop leading to unsaturated HSL values would erroneously alter the resulting color. (#2050)

Internals: Merged some changes to facilitate 1D->2D transition for some elements, and merging the stack layout PR (#846)

Travis: Fix (still not sure there is a way to test those files). (#1044)

Examples: Vulkan: Minor tweaks.

Travis: Added xcode build for the OSX+Metal example. (#1044) [@petmac]

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)

Documentation

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)

ImFontAtlas Comments (#2042) + added ImGuiFontAtlas_None for consistency.