Docking: Reorganizing some of the tab-bar selection and window focus related code.

Style: Added style.TabRounding setting.

Merge branch 'viewport' into docking

Merge branch 'master' into viewport ...

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

Docking: Fixed tab order restoring (follow up to 67be485e, broken in 455dc6e2)

Docking: Added DockBuilderRemoveNode() + various tweaks. Fixed dragging/undocking dock node from CollapseButton.

Docking: Some DockBuilder functions are applied on settings data if windows are not present. Added DockBuilderCreateNode which needs a size else if we can't split properly. DockNodeTreeSplit() doesn't clamp SizeRef. (+1 squashed commits)

TabBar: Recover if SelectedTabId doesn't exist anymore.

ArrowButton(): Fixed arrow shape being horizontally misaligned by (FramePadding.y-FramePadding.x) if they are different. ...

Demo: Added extra usage of AlignTextToFramePadding() in a more visible section.

Docking: Added undocking of whole dock node by dragging from the Collapse button. Super useful and works great!

Docking: Creating tab bar and adding window into tab bar immediately (not sure why I didn't do that before). Probably broke something subtle, will find out. *Edit* Initially broke restoring selected tab.

Docking: Internals: Transitioning some code toward consistently using ImGuiContext* ctx parameter instead of ImGuiDockContext

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

BeginMenu(): Fixed menu popup horizontal offset being off the item in the menu bar when WindowPadding=0.0f.

ColorPicker: Replaced the Separator with a Spacing call. (#2068)

Fix MSVC's C4312 warning about casting user texture type to void* in ImageButton (#2080)

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

DragFloat: Disabled using power curve when one edge is FLT_MAX (broken in 1.61). Disabled setting a default drag speed when one edge is FLT_MAX. (#2024)

DragFloat: Fixed a situation where dragging with value rounding enabled or with a power curve erroneously wrapped the value to one of the min/max edge. (#2024, #708, #320, #2075).

Nav, Focus: Fixed ImGuiWindowFlags_NoBringToFrontOnFocus windows not being restoring focus properly after the main menu bar or last focused window is deactivated.

Nav, Focus: Fixed ImGuiWindowFlags_NoBringToFrontOnFocus windows not being restoring focus properly after the main menu bar or last focused window is deactivated.

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

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

Docking: Added Docking system. Enable with io.ConfigFlags |= ImGuiConfigFlags_DockingEnable. (Part 1) (#351)

Tabs: Added BeginTabBar(), EndTabBar(), BeginTabItem(), EndTabItem() + demo. (#261, #351)

Version 1.66 WIP

Merge branch 'master' into viewport ...

# Conflicts:
#	imgui.cpp

Version 1.65