Fixed cursor issue caused by 6890e08b when calling BeginChild/EndChild multiple times to reappend into a same child window. (#2282)

Added a bunch of diagnostic ignore to cope with Clang -Weverything being absurd. Also fixed two legit warnings. (#2277)

Demo: Fixed bounds of DragFloat in Clipping section to avoid passing zero-sized to InvisibleButton().

imgui_freetype: Fixed redundant FT_Load_Glyph() calls, unused parameters, and compilation warning/error. (#2270)

ImFontAtlas: Fixed allocating for last bit (would only affect is that last codepoint is a multiple of 32). (#2270)

- Fixed abnormally high atlas height. (#618)
- Fixed support for any values of TexGlyphPadding (not just only 1). (#618)
- Atlas width is now properly based on total surface rather than glyph count (unless overridden with TexDesiredWidth). (#618)
- Fixed atlas builder so missing glyphs won't influence the atlas texture width. (#2233, #618)
- Fixed atlas builder so duplicate glyphs (when merging fonts) won't be included in the rasterized atlas. (#618)

- Atlas width is now properly based on total surface rather than glyph count (unless overridden with TexDesiredWidth).
- Fixed atlas builder so missing glyphs won't influence the atlas texture width. (#2233)
- Fixed atlas builder so duplicate glyphs (when merging fonts) won't be included in the rasterized atlas.

ImVector: Made reserve() another silly one-liner. It's not longer than other functions and our weird obsessions deserve to be carried with stringent consistence. + Comments

ImVector: Made a struct. Using T/T* in the code instead of value_type/iterator. Renamed index_from_pointer() to index_from_ptr() (was not documented, added in 1.63, users not supposed to use ImVector, hopefully not a big deal).

The various community projects that integrated Dear ImGui into Magnum
were merged together and are now an official part of the engine.

ImDrawList: Optimized some of the functions for performance of debug builds where non-inline function call cost are non-negligible.

Internals: LowerBound: Use raw pointer typedefs, we never use iterator anywhere else in the codebase.
Demo: Typo.
C98 fix.

Selectable() should have an ID even though they are disabled, to be consistent with other widgets. Not sure of the reasoning ~1.41 which made this turn to 0.

Fixed animated window titles from being updated when displayed in the CTRL+Tab list. + Adding overkill helpers for reusing buffers. (#787)

Renamed ImFont::GlyphRangesBuilder to ImFontGlyphRangesBuilder. Keep redirection typedef (will obsolete).

IO: Renamed InputCharacters[], marked internal as was always intended. AddInputCharacter() goes into a queue which can receive as many characters as needed during the frame. This is useful for automation to not have an upper limit on typing speed. Will later transition key/mouse to use the event queue later.

Nav: Fixed an keyboard issue where holding Activate/Space for longer than two frames on a button would unnecessary  keep the focus on the parent window, which could steal it from newly appearing windows. (#787)

Added bindings in Readme. Added internal IMGUI_DEBUG_LOG() helper. Comments, missing breaking changes note relative to imgui_impl_xxxx changes, not really part of core but worth adding in the imgui.cpp breaking change section.

Added sanity check to debug parent/child ordering issues (they would generally manifest with an assert/crash in EndFrame bu tthis assert will catch some earlier).