Minor tweaks to reduce false positive of PVS Studio static analyzer.

Menus: Tweaked horizontal overlap between parent and child menu (to help convey relative depth) from using style.ItemSpacing.x to style.ItemInnerSpacing.x, the later being expected to be smaller. (#1086)

Added IsItemActivated() as an extension to the IsItemDeactivated/IsItemDeactivatedAfterEdit functions which are useful to implement variety of undo patterns. (#820, #956, #1875)

InputText: Fixed redo buffer exhaustion handling (rare) which could corrupt the undo character buffer. (#2333)

Plot: Register an ID to take the click the same way as other framed widgets. Set HoveredId in the FramePadding zone (between inner_bb and frame_bb).

Internals: Selectable: Fixed rendering width miscalculation when starting pos is not line start pos, which would generally be unnoticeable. Could affect group lock X with a smaller SetCursorPos value but that's unlikely to be used.

Internals: EndGroup: Removed unnecesary parameter to ItemSize()

Internals: Removed unnecessary code.

Merge branch 'master' of https://github.com/ocornut/imgui

Tabs: Moved Tab List Popup to left-side to match docking button. Highlight selected tab. (#261, #351)

Tabs: Non-docking tab bars are storing names to allow tab list button + whole style scaling. Added ImGuiTabBarFlags_TabListPopupButton flag to show a popup button on manual tab bars. Locking FramePadding for the scope of a tab-bar to avoid sheering/clipping of tab item. Made scaling of tab ellipsis less awkward. (#261, #351)

ImGuiTextBuffer: Fix size() to allow using ImGuiTextBuffer with resize(0) patterns.

Update README.md

RadioButton: Fixed label horizontal alignment to precisely match Checkbox(). + Internals: Checkbox, RadioButton: Single call to ItemSize() for flow layout purpose.

Internals: DragScalar, SliderScalar: Calling ItemSize before ItemAdd as with every other widgets so we can more easily rearrange the signature of ItemXXX functions (toward allowing non-rounded sizes for scaling and flow layout).

Fonts: Fixed crash if FontGlobalScale is zero. Correctly debug naming default font if not 13 px. Demo: Moved PopupRounding along with other rounding values. Metrics: Displaying indexes with idx to be correct / less misleading.

Internals: Exposed internal SetWindowPos to imgui_internal.h (for imgui-test)

Removed io.DisplayVisibleMin/DisplayVisibleMax (which were marked obsolete and removed from viewport/docking branch already).

Examples: OpenGL3: Using GLSL 4.10 shaders for any GLSL version over 410 (e.g. 430, 450). (#2329) [@BrutPitt]

Internals: Tracking dummy select scope id (currently always zero) to facilitate merging of the range_select branch. (#1861)

Internals: Minor changes to TreeNodeBehavior() and Selectable() for the benefit of fhe range_select branch. (#1861)

Internals: Track ActiveIdHasBeenPressed (similar to ActiveIdHasBeenEdited). This is currently mostly for the benefit of the range_select branch. (#1861)

Merged from Docking branch: Various small changes, comments, typos fixes, moved blocks. To reduce overall drift. Should be no-op.

Merged from Docking branch: non-const ImVec2[] operator.

Fixed doc typo (#2326)

Updating supporter list.

Internals: InputScalarAsWidgetReplacement: Fixed seemingly unnecessary calling of SetActiveID/SetHoveredID every frame, which in turns allow us to remove the g.ActiveIdAllow/Block settings duplicated.

InputText: Fixed a bug where ESCAPE would be first captured by the Keyboard Navigation code. (#2321, #787)

InputText: Fixed a bug where ESCAPE would not restore the initial value in all situations. (#2321) [@relick]

imgui-test: Added extra item info callbacks. Using nav_bb for interactions when possible. Comments, Demo tweaks.