Refactor: Moved ColorEdit/ColorPicker/ColorButton/etc. functions from imgui.cpp to imgui_widgets.cpp (#2036)

Refactor: Moved Tree/Selectable functions from imgui.cpp to imgui_widgets.cpp (#2036)

Refactor: Moved Plot/Value functions from imgui.cpp to imgui_widgets.cpp (#2036)

Refactor: Moved Menu functions from imgui.cpp to imgui_widgets.cpp (#2036)

Refactor: Moved Combo/ListBox functions from imgui.cpp to imgui_widgets.cpp (#2036)

Refactor: Moved Button/Image/Checkbox/RadioButton/Bullet/ProgressBar functions from imgui.cpp to imgui_widgets.cpp (#2036)

Refactor: Moved Text functions from imgui.cpp to imgui_widgets.cpp (#2036)

Version 1.64 WIP

Version 1.63

Internals: Tidying up, moving helpers to imgui_internal.h (in prevision of 1.64 refactor)

ColorEdit4: Fixed a bug when text input or drag and drop leading to unsaturated HSL values would erroneously alter the resulting color. (#2050)

Internals: Merged some changes to facilitate 1D->2D transition for some elements, and merging the stack layout PR (#846)

Internals: Renaming of non-user facing parts from ValueChanged to Edited terminology. (#2034, #820, #956, #1875)

Renamed IsItemDeactivatedAfterChange() to IsItemDeactivatedAfterEdit() for consistency with new IsItemEdited() API. Kept redirection function (will obsolete fast as IsItemDeactivatedAfterChange() is very recent). (#820, #956, #1875, #2034)

Added IsItemEdited() to query if the last item modified its value (or was pressed). This is equivalent to the bool returned by most widgets. It is useful in some situation e.g. using InputText() with ImGuiInputTextFlags_EnterReturnsTrue. (#2034)

Internals: Wired a ImGuiItemStatusFlags_ValueChanged into ItemStatusFlags, for an hypothetical IsItemValueChanged() function. (#2034)

Rearrange header comments to find enums easily + fixed inconsistent sorting.

InputText: Improved sturdiness if the ResizeCallback purposefully modify data->BufTextLen or data->BufSize. (#2006, #1443, #1008)

InputText: Fix ResizeCallback callback on restoring initial value with Escape key. Avoid over-allocating for InitialText storage. (#2006, #1443, #1008)

Added optional misc/stl/imgui_stl.h wrapper to use with STL types (e.g. InputText with std::string). (#2035, #2006, #1443, #1008)

InputText: callback InsertChars() support resize callbacks correctly (followup to 24ff259) + fixed demo to use those functions. (#2006, #1443, #1008).

InputText: Fixed a few pathological crash cases on single-line InputText widget with multiple millions characters worth of contents. Because the current text drawing function reserve for a worst-case amount of vertices and how we handle horizontal clipping, we currently just avoid displaying those single-line widgets when they are over a threshold of 2 millions characters, until a better solution is found.

InputText: Fixed not tracking the cursor horizontally When modifying the text buffer through a callback.

ImDrawList: Large text passed to AddText() are being scanned for their end in order to avoid pre-reserving too many vertices.

Internals: InputText: Renaming. Comments.

InputText: Renamed ImGuiTextEditCallback to ImGuiInputTextCallback, ImGuiTextEditCallbackData to ImGuiInputTextCallbackData for consistency. Kept redirection types (will obsolete).

InputText: Added support for buffer size/capacity changes via the ImGuiInputTextFlags_CallbackResize flag. (#2006, #1443, #1008).

InputText: Internal renaming of some fields + final copy uses edit_state.CurLenA+1 instead of buf_size.

InputText: Fixed minor off-by-one issue when submitting a buffer size smaller than the initial zero-terminated buffer contents.

InputText: (Breaking change) removed ImGuiTextEditCallbackData::ReadOnly since it is a duplication of (ImGuiTextEditCallbackData::Flags & ImGuiInputTextFlags_ReadOnly) (#211)