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

Fixed bad merge (a82be53) where we lost the version number in Docking branch + moved Docking related API together for now.

Docking: Removed SplitRatio from ImGuiDockNode and ImGuiDockNodeSettings, which we don't need anymore.

Merge branch 'viewport' into docking ...

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

Docking: Internal renaming and comments. + Fixed DockNodeMoveChildNodes() to transfer the LastExplicitSize value (was inconsequential afaik).

Docking: Added ImGuiDockSpaceFlags_KeepAliveOnly, important for multiple level of tabs. (also renamed ImGuiDockFlags to ImGuiDockSpaceFlags.)

Merge branch 'master' into viewport ...

# Conflicts:
#	imgui.cpp
#	imgui_internal.h

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: Updating LastFrameActive earlier in Begin() because BeginDocked() will need to use it. Extracted some code into a DockNodeIsDropAllowedOne() function. Comments.

Docking: Added SetNextWindowUserType() + user type filtering in dockspace and window merging. Added DockSpace() flag ImGuiDockFlags_NoSplit. Renaming. Reworked the DockNodeUpdateFindOnlyNodeWithWindows code so DockNodeUpdate can access the first window.

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)

Docking: Added ImVec2[] non const operator. Added ImStrSkipBlank. Reseting some values earlier in Begin. Added IMGUI_DEBUG_LOG() helper. Added docking source code section.

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

Internals: Added ImPool helper structure. Moved ImVec1f.

Internals: Split RenderTextClipped into two functions.

Version 1.66 WIP

Merge branch 'master' into viewport ...

# Conflicts:
#	imgui.cpp

Version 1.65

Renamed stb_truetype.h to imstb_truetype.h, stb_textedit.h to imstb_textedit.h, and stb_rect_pack.h to imstb_rectpack.h. (#1718, #2036) ...

If you were conveniently using the imgui copy of those STB headers in your project, you will have to update your include paths.
The reason for this change is to avoid conflicts for projects that may also be importing their own copy of the STB libraries. Note that imgui's copy of stb_textedit.h is modified.

Viewport: Making the code a little more sturdy (flag changes) + added descriptions. (#1542)

Minor mostly inconsequential merges from Viewport + LoadIniSettingsFromMemory() entirely skip lines starting with ';'

Merge branch 'master' into viewport

Viewport: Moved code following refactor. (#2036, #1542)

Internals: Exposed SliderBehaviorT, DragBehaviorT, RoundScalarWithFormatT, SliderCalcRatioFromValueT. (#2036) ...

Renamed RoundScalarWithFormat -> RoundScalarWithFormatT.
Renamed SliderBehaviorCalcRatioFromValue -> SliderCalcRatioFromValueT

Version 1.65 WIP

Merge branch 'master_164' into viewport_164 ...

# Conflicts:
#	imgui.cpp
#	imgui_draw.cpp
#	imgui_widgets.cpp

Version 1.64

Refactor: Internals: Moved Settings functions in imgui.cpp in their own section. (#2036)