Merge branch 'features/ellipsis_rendering' ...

# Conflicts:
#	imgui.cpp

Internal: Offset STB_TEXTURE_K_ defines to remove that change from #2541 + sponsors update.

Font: Narrow ellipsis: various minor stylistic tweaks (#2775)

Columns: Separator: Fixed a bug where non-visible separators within columns would alter the next row position differently than visible ones. ...

Fixed rounding issues also leading to change of ScrollMax depending on visible items (in particular negative coordinate would be rounded differently)

Nav, Scrolling: Added support for Home/End key. (#787)

Fix DragScalar for unsigned types (#2780) ...

decreasing the value was broken on arm64

Backends: OpenGL3: Tweaked initialization code allow application calling ImGui_ImplOpenGL3_CreateFontsTexture() before ImGui_ImplOpenGL3_NewFrame() if for some reason they wanted.

ColorEdit: Disable Hue edit when Saturation==0 instead of letting Hue values jump around.

DragInt, DragFloat, DragScalar: Using (v_min > v_max) allows locking any edit to the value.

TabBar: feed desired width (sum of unclipped tabs width) into layout system to allow for auto-resize. (#2768) ...

Before 1.71 tab bars fed the sum of current width which created feedback loops in certain situations. Amend f95c77e.

TabBar: improved shrinking for large number of tabs to avoid leaving extraneous space on the right side. Individuals tabs are given integer-rounded width and remainder is spread between tabs left-to-right.

Added a mechanism to compact/free the larger allocations of unused windows (buffers are compacted when a window is unused for 60 seconds, as per io.ConfigWindowsMemoryCompactTimer = 60.0f). Note that memory usage has never been reported as a problem, so this is merely a touch of overzealous luxury. (#2636)

SliderScalar: Improved assert when using U32 or U64 types with a large v_max value. (#2765) ...

+  misc minor stuff.

Rebased imstb_rectpack on stb_rect_pack v1.00.

ImDrawList: clarified the name of many parameters so reading the code is a little easier. (#2740)

Using offsetof() when available in C++11. Avoids Clang sanitizer complaining about old-style macros. (#94)

TabBar: fixed single-tab not shrinking their width down. ...

+ minor typo fixes (#2738)

TabBar: fixed ScrollToBar request creating bouncing loop when tab is larger than available space.

ColorPicker: Made rendering aware of global style alpha of the picker can be faded out. (#2711) ...

Note that some elements won't accurately fade down with the same intensity, and the color wheel when enabled will have small overlap glitches with (style.Alpha < 1.0).

Backends: Vulkan: Added support for specifying multisample count. (#2705, #2706)

Backends: DX11: Fixed GSGetShader() call not passing an initialized instance count, would generally make the debug layer complain (Added in 1.72).

Version 1.73 WIP

Version 1.72b (patch for nav)

Nav: Made hovering non-MenuItem Selectable not re-assign the source item for keyboard navigation.

Scrolling, Nav: Fixed programmatic scroll leading to a slightly incorrect scroll offset when the window has decorations or a menu-bar (broken in 1.71). This was mostly noticeable when a keyboard/gamepad movement led to scrolling the view, or using e.g. SetScrollHereY() function. Fix/amend a0994d74.

Internal: Moved NavScrollToBringItemIntoView() declaration to imgui_internal.h. Fixed spacing missing in 494d804. Fixed changelog wreck from 1.72.

Version 1.73 WIP

Version 1.72

Internal: Added IsMouseDragPastThreshold(). Tweaks. Todo. ...

Demo: Showing how to use the format parameter of Slider/Drag functions to display the name of an enum value instead of the underlying integer value

Scrolling: Made mouse-wheel scrolling lock the underlying window until the mouse is moved again or until a short delay expires (2 seconds). This allow uninterrupted scroll even if child windows are passing under the mouse cursor. (#2604)