Misc comments, internal renaming, added disable indentation option to Columns demo section.

Internals: ImHashStr() default parameter.

Added SetNextItemWidth() helper to avoid using PushItemWidth/PopItemWidth() for single items.

Added commentary about ContentRegion functions. Added internal GetContentRegionMaxScreen() to facilitate internal code at the moment.

Internals: Moved CalcItemSize next to CalcItemWidth, added comments to clarify their respective intent. Should have no side effect.

Internals: Columns: Tweaks, renaming. Metrics: Show rectangles for child windows. ...

Renamed SameLine() first parameter.

Merged a bunch of small changes from Docking branch to reduce the difference between branches. ...

Noticeable: horizontal alignment of CloseButton. Menu fill take account of border. Various stylistic tweaks to accomodate other changes in Docking.

Internals: Columns: Some renaming, extracted code into GetColumnsID().

Tests: Added hook/tweaks for imgui-test engine. + Fixed warnings.

Internals, Docs: Added a bunch of clarification about ButtonBehavior in the form of a table (and to facilitate writing tests)

Internals: Merge minor things from range_select branch. Added ImGuiButtonFlags_NoHoveredOnNav. Added IsItemToggledSelected() - unused here. Renaming.

Internals: Selectable: Added ImGuiSelectableFlags_AllowItemOverlap in imgui_internal.h (~ #684, #2341)

InputText: Made Shift+Tab consistently do nothing regardless of whether the back-end emits both char and keys or just keys. (#2467, #1336)

Internals: Renamed the ImGuiWindow HiddenFrameXXX fields to decorrelate them from resizing behavior, as those values are set by other logic.

Comments, todo list, remove trailing spaces.

Version 1.70 WIP

Version 1.69, comments, typos

TabBar: Reworked scrolling policy (when ImGuiTabBarFlags_FittingPolicyScroll is set) to teleport the view when aiming at a tab far away the visible section, and otherwise accelerate the scrolling speed to cap the scrolling time to 0.3 seconds.

Internal: Removed unused fields from ImGuiMenuColumns.

Fix typos. (#2413)

Don't use const qualified parameters in declarations. ...

This fixes warnings from clang-tidy like this:

    parameter 'v_max' is const-qualified in the function declaration;
    const-qualification of parameters only has an effect in function definitions

Since values (rather than references or pointers) don't need to be
const, they don't need to be marked that way in the function declaration.

Added InputTextWithHint() (#2400) ...

Squashed commit of the following:

commit 1970d84
Author: Lucas Lazare <lazarelucas@yahoo.fr>
Date:   Tue Mar 5 12:20:39 2019 -0500

    Removing sneaky tabulations #2 (why, editor T-T)

    I should update my settings, I guess

commit 219bdfc
Author: Lucas Lazare <lazarelucas@yahoo.fr>
Date:   Tue Mar 5 12:17:27 2019 -0500

    Removing useless check introduced in b0d172

commit 8afd7a2
Author: Lucas Lazare <lazarelucas@yahoo.fr>
Date:   Tue Mar 5 11:49:24 2019 -0500

    Removing sneaky tabulations

commit 8e04908
Author: Lucas Lazare <lazarelucas@yahoo.fr>
Date:   Tue Mar 5 11:45:13 2019 -0500

    Moving InputTextHinted code to InputTextEx

commit b0d1723
Author: Lucas Lazare <lazarelucas@yahoo.fr>
Date:   Tue Mar 5 00:23:02 2019 -0500

    C++11 to C++98

commit 9afeae3
Author: Lucas Lazare <lazarelucas@yahoo.fr>
Date:   Mon Mar 4 23:43:28 2019 -0500

    Added InputTextHinted

Internal: Tabbing/Focus: Tidying up old code, moved some state to context instead of window. Storing new data will allow us to fix the bug mentioned in #2215 (probably in next commit).

Internal: Tabbing: Tweaks to FocusableItemRegister and using the standard mechanism to allow/block Tab being interpreting by tabbing instead of InputText() widget.

Internal: Text: Extracted TextUnformatted into TextEx over which we can freely atter the signature. Clarified current large text behavior of TextUnformatted with explicit ImGuiTextFlags_NoWidthForLargeClippedText flag (always set).

Renamed GetOverlayDrawList() to GetForegroundDrawList() for consistency. Kept redirection function (will obsolete). (#2391) ...

Demo: Using GetBackgroundDrawList() and GetForegroundDrawList() in "Custom Rendering" demo.

Added GetBackgroundDrawList() helper to quickly get access to a ImDrawList that will be rendered behind every other windows. (#2391)

InputInt, InputScalar: +/- buttons now respects the natural type limits instead of overflowing or underflowing the value.

InputText: Fixed various display corruption related to swapping the underlying buffer while a input widget is active (both for writable and read-only paths). Often they would manifest when manipulating the scrollbar of a multi-line input text.

Internal: InputText: Minor changes (intended to have side-effect but clarify next commit, however there is rarely such a thing as zero side effect in InputText land!)