Version 1.70 WIP

Merge branch 'master' into docking ...

# Conflicts:
#	docs/CHANGELOG.txt
#	examples/example_win32_directx10/main.cpp
#	examples/example_win32_directx11/main.cpp
#	examples/example_win32_directx12/main.cpp
#	examples/example_win32_directx9/main.cpp

Version 1.69, comments, typos

Viewport: DestroyPlatformWindow() skips calling user function if PlatformWindowCreated is set. + Clarified comment about implicit Debug viewport which may be hogging a viewport.

Fixed main viewport not being marked as created, which broke updating the IME input position for the main viewport. ...

This change also removes the logic scattered about that compensated for PlatformWindowCreated being wrong for the main viewport.

Internals: Fixed Navigation from reaching ImGuiItemFlags_Disabled items (#211) + Examples comments

Docking: Fixed node merging altering window position incorrectly in a way that would make SizeContents incorrect for the next frame (making scrollbar flicker). (#2414, #2109)

Viewport: Popups and Tooltips viewports are correctly parented to the parent window's viewport. (#2409, #1542)

Merge branch 'master' into docking ...

# Conflicts:
#	examples/example_win32_directx11/main.cpp
#	examples/example_win32_directx12/main.cpp
#	examples/example_win32_directx9/main.cpp
#	imgui.cpp

Viewports: Fixed delayed window pos->viewport pos sync leading to monitor not being updated at the time of clamping window position in Begin. (#2415, #1542)

Viewports: Renamed ConfigViewportsNoParent to ConfigViewportsNoDefaultParent. Fix outdated comments in examples.

Docking: Fixed an issue where removing the last window from a dockspace node that is not a central node without remove the node. (#2414, #2109)

Fix typos. (#2413)

Don't use const qualified parameters in declarations. ...

This fixes warnings from clang-tidy like this:

    parameter 'v_max' is const-qualified in the function declaration;
    const-qualification of parameters only has an effect in function definitions

Since values (rather than references or pointers) don't need to be
const, they don't need to be marked that way in the function declaration.

Moved placeholder sections to match Docking branch. Comments.

Merge branch 'master' into docking

Refactor: Move viewport code under other subsystem to simplify merging (4) (moving in multiple commits to make diff/patch behave nicely)

Refactor: Move viewport code under other subsystem to simplify merging (3) (moving in multiple commits to make diff/patch behave nicely)

Refactor: Move viewport code under other subsystem to simplify merging (2) (moving in multiple commits to make diff/patch behave nicely)

Refactor: Move viewport code under other subsystem to simplify merging (1) (moving in multiple commits to make diff/patch behave nicely)

Internal: Columns: Allow to use BeginColumns(1) so code designed for variable number of columns can still call NextColumn etc. (#125)

Fix for Android char being unsigned by default (#2408)

Merge branch 'master' into docking ...

# Conflicts:
#	imgui.cpp
#	imgui_internal.h

Fixed IsItemDeactivated()/IsItemDeactivatedAfterEdit() from not correctly returning true when tabbing out of a focusable widget (Input/Slider/Drag) in most situations. (#2215, #1875) ...

+ Minor renaming of a local variable in widget code.

Internal: Tabbing/Focus: Tidying up old code, moved some state to context instead of window. Storing new data will allow us to fix the bug mentioned in #2215 (probably in next commit).

Internal: Tabbing: Tweaks to FocusableItemRegister and using the standard mechanism to allow/block Tab being interpreting by tabbing instead of InputText() widget.

Nav: Fixed Ctrl+Tab keeping active InputText() of a previous window active after the switch. (#2380)

Merge branch 'master' into docking ...

# Conflicts:
#	imgui.cpp
#	imgui.h
#	imgui_internal.h

Renamed GetOverlayDrawList() to GetForegroundDrawList() for consistency. Kept redirection function (will obsolete). (#2391) ...

Demo: Using GetBackgroundDrawList() and GetForegroundDrawList() in "Custom Rendering" demo.

Added GetBackgroundDrawList() helper to quickly get access to a ImDrawList that will be rendered behind every other windows. (#2391)