The Bullet and Leaf ImGuiTreeNodeFlags are now taken into account for Framed/CollapsingHeader tree nodes as well. TreeNodeEx() can be used to specify these flags. A choice was made to left-adjust the Framed text when no Bullet/Arrow is rendered, since this was deemed to look better in the Framed context (especially when considering that CollapsingHeader is drawn using NoTreePushOnOpen, so child/sibling Text items etc will often be non-indented).
Issue is fixed by storing last active color picker color and last hue value when active color picker takes rgb as input. Then if current color picker color matches last active color - hue value will be restored. IDs are not used because ColorEdit4() and ColorWidget4() may call each other in hard-to-predict ways and they both push their own IDs on to the stack. We need hue restoration to happen in entire stack of these widgets if topmost widget used hue restoration. Since these widgets operate on exact same color value - color was chosen as a factor deciding which widgets should restore hue.
This changeset implements several pieces of the puzzle that add up to a narrow ellipsis rendering.
## EllipsisCodePoint
`ImFontConfig` and `ImFont` received `ImWchar EllipsisCodePoint = -1;` field. User may configure `ImFontConfig::EllipsisCodePoint` a unicode codepoint that will be used for rendering narrow ellipsis. Not setting this field will automatically detect a suitable character or fall back to rendering 3 dots with minimal spacing between them. Autodetection prefers codepoint 0x2026 (narrow ellipsis) and falls back to 0x0085 (NEXT LINE) when missing. Wikipedia indicates that codepoint 0x0085 was used as ellipsis in some older windows fonts. So does default Dear ImGui font. When user is merging fonts - first configured and present ellipsis codepoint will be used, ellipsis characters from subsequently merged fonts will be ignored.
## Narrow ellipsis
Rendering a narrow ellipsis is surprisingly not straightforward task. There are cases when ellipsis is bigger than the last visible character therefore `RenderTextEllipsis()` has to hide last two characters. In a subset of those cases ellipsis is as big as last visible character + space before it. `RenderTextEllipsis()` tries to work around this case by taking free space between glyph edges into account. Code responsible for this functionality is within `if (text_end_ellipsis != text_end_full) { ... }`.
## Fallback (manually rendered dots)
There are cases when font does not have ellipsis character defined. In this case RenderTextEllipsis() falls back to rendering ellipsis as 3 dots, but with reduced spacing between them. 1 pixel space is used in all cases. This results in a somewhat wider ellipsis, but avoids issues where spaces between dots are uneven (visible in larger/monospace fonts) or squish dots way too much (visible in default font where dot is essentially a pixel). This fallback method obsoleted `RenderPixelEllipsis()` and this function was removed. Note that fallback ellipsis will always be somewhat wider than it could be, however it will fit in visually into every font used unlike what `RenderPixelEllipsis()` produced.
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).
