+ Update readme and mission statement.
Removed "Minimize screen reel-estate usage", removed details on memory consumption (still very valid, just too much noise in a mission statement)

CheckboxFlags: Display mixed-value/tristate marker when passed flags that have multiple bits set and stored value matches neither zero neither the full set.

ImGuiListClipper: Renamed constructor parameters which created an ambiguous alternative to using the ImGuiListClipper::Begin() function, with misleading edge cases.

Compiling the code as-is results in the following warning:

-->8--
imgui_freetype.cpp:341:72: warning: ‘void* memset(void*, int, size_t)’
        clearing an object of type ‘struct ImFontBuildSrcDataFT’ with no
        trivial copy-assignment; use assignment or value-initialization
        instead [-Wclass-memaccess]
  341 |     memset(src_tmp_array.Data, 0, (size_t)src_tmp_array.size_in_bytes());
      |                                                                        ^
imgui_freetype.cpp:302:8: note: ‘struct ImFontBuildSrcDataFT’ declared here
  302 | struct ImFontBuildSrcDataFT
      |        ^~~~~~~~~~~~~~~~~~~~
--8<--

This is caused by presence of ImVector<> directly in ImFontBuildSrcDataFT data
structure, as well as in the child ImBitVector. Since ImVector<> has a
constructor, the compiler infers that initialization by memset is not valid.
Such initialization is not a bug, however, as the default ImVector<> ctor just
sets the structure data members to 0, which is exactly what the memset does.

Casting the data structure address to void* pointer silences this warning.

ImVector: Stricter bound-checking asserts. Fix warnings: trailing comma (old compilers), zealous preprocessor warnings.

+ Link to CI actions added in 3be352fc

ImGuiListClipper: internal rework and tidying up to facilitate supporting frozen rows in tables + stop promoting using constructors parameters.

Style: Renamed style.TabMinWidthForUnselectedCloseButton to style.TabMinWidthForCloseButton. Fixed README links.

Tab Bar: Tidying up. Rework ShrinkWidths to allow marking tabs as not shrinkable (unused yet) + don't unnecessarily move data within ShrinkWidthBuffer. (#3291)

Tab Bar: Fix reorderable tab bars. Fix misleading use of tab_max_width in TabBarLayout(). Misc amends, shortening. (#3291)

Tab Bar: Fixed handling of scrolling policy with leading/trailing tabs. + warning fixes + bunch of renaming.  (#3291)

Demo tweaks.

Tab Bar: Added TabItemButton(), ImGuiTabItemFlags_Leading, ImGuiTabItemFlags_Trailing + demo. (#3291)

(squashed various commits by 2 authors)

Internals, CollapsingHeader, TabItem: Standardized using a #CLOSE id prefix for TabItem and ColllapsingHeader (same as window)

Tab Bar: Fixed a small bug where scrolling buttons (with ImGuiTabBarFlags_FittingPolicyScroll) would generate an unnecessary extra draw call.

Tab Bar: Fixed a small bug where closing a tab that is not selected would leave a tab hole for a frame.

Removed return value from OpenPopupOnItemClick(). Use IsWindowAppearing() after BeginPopup() for a similar result.

+ fix stb_textedit.h to build with C language (amend fbf70070)

(contents of 20200412.zip's dx11.exe is flagged by Windows Defender, can't currently repro)

+ Fonts: AddFontDefault() adjust its vertical offset based on floor(size/13) instead of always +1.

InputText: Fixed minor inconsistency when pressing Down on the last line when it doesn't have a carriage return (it used to move to the end of the line)

+ fixed two of our typos in stb_textedit.h

# Conflicts:
#	docs/CHANGELOG.txt

(nb: GLEW sets the define we previously used)

Bypass unnecessary formatting when using the TextColored()/TextWrapped()/TextDisabled() helpers with a "%s" format string. (#3466)