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)

Merge branch 'master' into docking ...

# Conflicts:
#	examples/imgui_impl_opengl3.cpp

Misc: Asserting in NewFrame() if style.WindowMinSize is zero or smaller than (1.0f,1.0f). Internal: ImHash functions tweaks. Added InputText() to query status section.

Merge branch 'master' into docking ...

# Conflicts:
#	imgui.cpp
#	imgui.h

Renamed ColorEdit/ColorPicker's ImGuiColorEditFlags_RGB/_HSV/_HEX flags to respectively ImGuiColorEditFlags_DisplayRGB/_DisplayHSV/_DisplayHex. This is anticipation of adding new flags to ColorEdit/ColorPicker functions which would make those ambiguous. (#2384) [@haldean]

Moved Settings section above Docking to facilitate master<>docking merges.

Moved Logging/Capturing section above Docking to facilitate master<>docking merges.

Merge branch 'master' into docking ...

# Conflicts:
#	imgui.cpp

Fixes warning caused by a missing switch/case. (#2382, #2381)

Log/Capture: Fixed extraneous leading carriage return. Fixed an issue when empty string on a new line would not emit a carriage return.

Log/Capture: Fixed LogXXX functions 'auto_open_depth' parameter being treated as an absolute tree depth instead of a relative one. Fixed CollapsingHeader trailing ascii representation being "#" instead of "##". Minor tidying up the of code.

Internal: Log/Capture: Rework to add an internal LogToBuffer() function which is useful for writing automated tests. Clarified logging state by adding an enum.

Nav: Fixed a tap on AltGR (e.g. German keyboard) from navigation to the menu layer. (follow and extend on e.g #369, #370)

Merge branch 'master' into docking ...

# Conflicts:
#	docs/CHANGELOG.txt
#	examples/imgui_impl_opengl3.cpp
#	imgui_widgets.cpp

Internal: InputText: Renamed is_editable to !is_readonly, Hopefully more explicit. Renamed internal member. Shuffled some code. Added comments, assert (_will_ trigger on !readonly > readonly edge, old bug).

Version 1.69 WIP