Merge branch 'master' into docking ...

# Conflicts:
#	examples/imgui_impl_dx10.cpp
#	examples/imgui_impl_dx11.cpp
#	examples/imgui_impl_dx9.cpp
#	examples/imgui_impl_opengl3.cpp
#	imgui.h
#	imgui_demo.cpp

Renamed ImGuiBackendFlags_HasVtxOffset to ImGuiBackendFlags_RendererHasVtxOffset to match naming convention already used in viewport/docking branch. (#2591) + Fix OpenGL3 code missing flag.

Merge branch 'master' into docking ...

# Conflicts:
#	examples/imgui_impl_dx10.cpp
#	examples/imgui_impl_dx10.h
#	examples/imgui_impl_dx11.cpp
#	examples/imgui_impl_dx11.h
#	examples/imgui_impl_dx9.cpp
#	examples/imgui_impl_dx9.h
#	examples/imgui_impl_opengl3.cpp
#	examples/imgui_impl_opengl3.h
#	examples/imgui_impl_osx.h
#	examples/imgui_impl_osx.mm
#	imgui.cpp
#	imgui.h
#	imgui_demo.cpp
#	imgui_internal.h

ImDrawList: Added ImDrawCmd::VtxOffset value to support large meshes (64k+ vertices) using 16-bits indices. To enable the feature, the renderer back-end needs to set 'io.BackendFlags |= ImGuiBackendFlags_HasVtxOffset' and honor the ImDrawCmd::VtxOffset field. Otherwise the value will always be zero. This has the advantage of preserving smaller index buffers and allowing to execute on hardware that do not support 32-bits indices. ...

ImDrawList: Added ImDrawCmd::IdxOffset value, equivalent to summing element count for each draw command. This is provided for convenience and consistency with VtxOffset. (#2591)

ImDrawList: Store initial flags for the frame in ImDrawListSharedData, reducing code duplication in setting up the flags.

Internal: Renamed InnerMainRect to InnerVisibleRect. Printing coordinates in Metrics window.

Docking: Fixed DockBuilderRemoveNode() from overwriting other parent node flags when trying to move the CentralNode flag.

Docking: Saving local _NoResize flag. (#2583)

Added full "Dear ImGui" prefix to the title of "Dear ImGui Demo" and "Dear ImGui Metrics" windows. Shortened amount of nodes in columns>tree demo.

Docking: Saving the NoTabBar, NoWindowMenuButton, NoCloseButton fields of dock node into the .ini file. Added them to the Metrics window. (#2583, #2423, #2109).

Docking: Clarified terminology of docking/tablist/collapse button into Window Menu button matching master. Added private ImGuiDockNodeFlags_NoWindowMenuButton, ImGuiDockNodeFlags_NoCloseButton flags. (#2583, #2109)

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!)