fixed incomplete replacement of unsigned short with ImWchar in interface of ImFont::FindGlyph

Minor tweak, removed extraneous empty destructor.

TreePush with zero arguments was ambiguous. Resolved by making it call TreePush(const void*)

NewFrame() now asserts if neither Render or EndFrame have been called. Exposed EndFrame(). Made it legal to call EndFrame() more than one. (#1423 etc.)

NewFrame(): using literal strings in the most-frequently firing IM_ASSERT expression to increase the odd of programmers seeing them (especially those who don't use a debugger).

Merge pull request #1445 from franciscod/uninitialized_o3_werror ...

ImFontAtlas: Fix maybe-uninitialized warning.

Demo: Fix warning "format not a string literal and no format arguments" for over-zealous compilers settings. (#1450, #1451)

Added comment about TextUnformatted(). (#1450)

Combo: Offset popup position by border size so that a double border isn't so visible. (#707)

Style: Added PopupRounding setting. (#1112)

Fix IsItemHovered() returning true for non-title bar hidden items that are clipped due to window collapsing logic. Fix 27fd1b9. (#823)

Internals: Renamed ImGuiWindow::Accessed to WriteAccessed.

Style: Made changes to Classic style (!!!). Tweaked Dark style. (#707)

Style: Added a default StyleColorsLight(). (#707)

Demo: Tweaks.

Style: Removed ImGuiCol_ComboBg in favor of combo boxes using ImGuiCol_PopupBg for consistency. (#707)

Style Editor: Using local storage so Save/Revert button made some more sense without code passing its storage. Tweaked layout, added horizontal scroll bar, Fixed Save/Revert button to be always accessible. (fix #1211)

Style Editor: Sneakily adding a combo box to change colors (#707)

Style: Dark: Tweaks + setting BorderShadow correctly.

Internals: Window minor internal renaming + added WindowRounding latch.

Style: renamed style.ChildWindowRounding to style.ChildRounding, ImGuiStyleVar_ChildWindowRounding to ImGuiStyleVar_ChildRounding.

Merge pull request #1448 from codecat/minor-fixes ...

Examples: DirectX: fix wrong comment in dx implementation headers

Fix wrong comment in dx implementation headers

Style: ScaleAllSizes() helper rounds down every values so they are aligned on integers.

fix uninitialized atlas packing context

Columns: Added ImGuiColumnsFlags_GrowParentContentsSize to internal API to restore old content sizes behavior. (#1444, #125)

Internals: Updating condition/allow flags with a function.

Internals: Window: Store whether the windows has a close button (we need that info for window/tabs dropping preview calculation)

Internals: Added BringWindowToFront(), BringWindowToBack() helpers.

Windows with MenuBar have a larger minimum height to avoid artefacts (I fixed most of the vertical/horizontal artefacts, but the ones in rounded corners were too hard to fix).