Fixed scrollbar issue, followup to beda5fc and 2df8fa9.

Internals: Cleanup FindBestPopupWindowPos() to be more digestible, since we are bounds to rework the logic there. No functional changes intended. FIXED TYPO.

Internals: Cleanup FindBestPopupWindowPos() to be more digestible, since we are bounds to rework the logic there. No functional changes intended

Exposed GetOverlayDrawList(). (~#545, ~#530)

Begin: Move the code that update the Appearing flag above the BeginDocked() branch.

Fixed scrollbar enable/disable calculation when size is modified programmatically. This is the generalization of the fix in 2df8fa9.

Lower-right resize grip only appears when hovered. (#822)

Comments about ImGuiWindowFlags_ResizeFromAnySide. Removed hovering color. May need its own color. (#822)

Windows can be resized from their borders when ImGuiWindowFlags_ResizeFromAnySide is set. (#822) The interaction is currently unsatisfying because we can only reach a window from its inner rectangle (because of HoveredWindow filtering).

Tweak four-corners resize grip code. Added ImRect::FixInverted() helper. (#822)

Added ImGuiWindowFlags_ResizeFromAnySide flag and code to resize from any of the 4 corners (only 2 corners enabled). (#822)

Fixed a one frame glitch, when window claiming focus themselves on appear, the title bar wouldn't use the focused color on that frame.

Internals: Splitter Behavior doesn't show a border. (#319)

Style: Tweaked default WindowRounding value from 9 to 7 (#707)

Scrolling: SetScrollFromPosY() tweak to match change in a0d53fe with similar desirable jump/discontinuity at each limit to skip the (ItemSpacing>WindowPadding) difference (followup to 0e5b64e, #150)

Style, Scrolling: Fixed padding and scrolling asymetry where lower/right sides of a window wouldn't use WindowPadding properly + causing minor scrolling glitches.

Internals: Removed unnecessary duplicate scrolling code + added extra infos to Metrics window.

Settings: Internals: Renaming.

Settings: Internals: Simplifying code a bit. Creating Settings structure during first save. Windows where ImGuiWindowFlags_NoSavedSettings was late toggled will save settings correctly. (#1000)

Settings: Internals: Added FindSettingsHandler()

Settings: Internals: Exposed FindWindowSettings(). Simplified some code.

Settings: Internals: Renamed ImGuiSettingsWindow to ImGuiWindowSettings.

Build fix

Settings: Import old style .ini file

Settings: Make ImGuiWindow settings always first in the list.

Settings: Initializing ImGuiSettingsWindow so external users don't end up with uncleared data. Exposed MarkIniSettingsDirty() in imgui_internal.h

Settings: basic refactor so that additional data structures can be loaded/saved. Parser/saver is still the minimum viable poor-man parsing.

Settings: Internal renaming of structure and fields names.

Settings: Basic internal refactor to have functions for saving from/to memory (not exposed)

ImGuiTextBuffer: Renamed append() helper to appendf(), appendv() to appendfv(). Added reserve().