Docking: Honor style.WindowMenuButtonPosition setting in docking node.

Merge branch 'master' into docking ...

# Conflicts:
#	imgui.cpp
#	imgui_internal.h
#	imgui_widgets.cpp

Style: Added style.WindowMenuButtonPosition (left/right, defaults to ImGuiDir_Left) to move the collapsing/docking button to the other side of the title bar.

Internal: CloseButton takes an upper-left corner + a size to be consistent with similar widgets.

Merge branch 'master' into docking ...

# Conflicts:
#	imgui.cpp
#	imgui_internal.h

Internals: Added InnerWorkRect equal to old InnerClipRect, added InnerWorkRectClipped actually clipped.

Fix OuterRectClipped not being clipped correctly, which resulted in child window outside visible bound to not be marked with SkipItems. Broken in b50c61c. ...

+ Comments on InnerClipRect being misleading. Demo: Tweak to sizing of child window in the Layout->Scrolling section.

Merge branch 'master' into docking ...

# Conflicts:
#	imgui.cpp

Fixed crash when appending with BeginMainMenuBar() more than once and no other window are showing. (#2567) + comments

BeginPopupContextItem(): Skip processing when SkipItems is set as LastItemId is unreliable and we assert when it is zero. + Minor comments on columns.

Fixed GCC mem-access warnings (#2565) ...

+ using "if defined" more consistently for Clang.

Docking: Fixed temporarily losing Dockspace flag when merging remaining sibling back into a parent node. (#2563, #2109) ...

Would trigger an assert in the Passthru hole path. Broken by fd5859ed.

Docking: Fixed undocking whole node (from collapse/docking menu button) from losing its size/pos. Made collapose/docking menu id easier to compute for testing.

Update changelog, comments, made empty/no-text clipboard return NULL as with other implementation. Minor style tweaks. (#2546) ...

Fixed IMGUI_DISABLE_WIN32_FUNCTIONS not disabling IME code.

Add native mac copy/paste support to match win32 (#2546)

Docking: Fixed incomplete merge of 36e714a leading to undocking. #2109

Merge branch 'master' into docking ...

# Conflicts:
#	examples/imgui_impl_glfw.cpp
#	examples/imgui_impl_win32.cpp
#	imgui.cpp
#	imgui_internal.h

Fixed uses of IsItemDeactivated(), IsItemDeactivatedAfterEdit() on multi-components widgets and after EndGroup(). (#2550, #1875)

Internal: Renamed fields + minor tweaks (probably shallow break stack-layout pr, sorry!)

Internal: Removed GetNextItemWidth(), relying on ItemAdd or NextItemData.ClearFlags() to clear the width data. Amend 5078fa20 and undo some of its effects of imgui_widgets.cpp

Renamed SetNextTreeNodeOpen() to SetNextItemOpen(). Refactored SetNextItemXXX stuff to match SetNextWindowXXX code closely.

Internal: Storing flags for NextWindowData so that we can clear everything with a single write and remove dummy condition fields.

Internal: Minor tidying/reordering of sections within ImGuiContext / window DC.

Tweak EndGroup() to facilitate fixing #2550 later (currently should have no side-effect0. Demo: Add extra widget to status query test.

Fixed unused variables warnings when asserts are compiled out. (#2551)

Cast ImTextureId to void* before printing in Metrics window. (#2548)

IO: changed AddInputCharacter(unsigned short c) signature to AddInputCharacter(unsigned int c). ...

Examples/Backends: Don't filter characters under 0x10000 before calling io.AddInputCharacter(), the filtering is done in io.AddInputCharacter() itself. This is in prevision for fuller Unicode support. (#2538, #2541)

Fixed a PVS Studio static analyzer warning.

Merge branch 'master' into docking ...

# Conflicts:
#	docs/CHANGELOG.txt
#	imgui.cpp

Internal: Extracted some of the Begin code into RenderWindowDecorations().