Merge branch 'master' into docking ...

# Conflicts:
#	docs/CHANGELOG.txt

Internals: Columns: Poke into WorkRect and use them in the GetContentRegionMax() functions. This should be a no-op, but preparing us to transition toward using WorkRect instead of ContentRegionRect. ...

Removed one use of ContentsRegionRect.

Disable -Wpragmas warning in GCC to avoid relying on version checks, as unusual/forks/mods don't appear to always have same warning<>version. (#2618) ...

+ Fix version number in imgui.h

Merge branch 'master' into docking ...

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

Version 1.72 WIP

Merge branch 'master' into docking ...

# Conflicts:
#	docs/CHANGELOG.txt
#	examples/README.txt
#	imgui.cpp
#	imgui.h
#	imgui_internal.h
#	imgui_widgets.cpp

Version 1.71 + comments

Readme, comments, dear imgui prefixes

Log/Capture: Fixed BeginTabItem() label not being included in a text log/capture. ...

Extracted tab rendering code into a RenderTextEllipsis() function.

Internals: Added drawlist and color arg to RenderArrow(), RenderBullet(). Reordered args for RenderPixelEllipsis.

imgui-test: Added IMGUI_TEST_ENGINE_LOG macro to emit into test log from core or user land.

Made PushID() behave the same in 32-bit and 64-bit, by not padding the integer into a void*. (Also technically faster.)

Synced/merged minor cruft from docking branch to minimize drift. AFAIK the only meaningful no-op change is that the call UpdateHoveredWindowAndCaptureFlags() was moved above UpdateMouseMovingNewFrame() to match what docking branch has been doing for a while.

Merge branch 'master' into docking ...

# Conflicts:
#	imgui.cpp
#	imgui_internal.h

Internals: Storing ScrollMax into a member. Mostly to facilitate debugging. Also locking down window->Scroll slightly lower in the Begin function.

Internals: Renamed SizeContents to ContentSize, SizeContentsExplicit to ContentSizeExplicit. Tweaked Metrics->Show Rectangles functionality.

Window rectangles: Changed WorkRect to cover the whole region including scrolling (toward obsolete ContentsRegionRect) + using full WindowPadding*1 padding. ...

Tweaked InnerClipRect.
TreeNode, CollapsingHeader: Fixed highlight frame not covering horizontal area fully when using horizontal scrolling. (#2211, #2579)
TabBar: Fixed BeginTabBar() within a window with horizontal scrolling from creating a feedback loop with the horizontal contents size.
Columns: Fixed Columns() within a window with horizontal scrolling from not covering the full horizontal area (previously only worked with an explicit contents size). (#125)
Demo: Added demo code to test contentsrect/workrect

Clarified behavior of SetNextWindowContentSize(). Content size is defined as the size available after removal of WindowPadding on each sides. So SetNextWindowContentSize(ImVec2(100,100)) + auto-resize will always allow submitting a 100x100 item without creating a scrollbar, regarding of WindowPadding.The exact meaning of ContentSize for decorated windows was previously ill-defined.

Merge branch 'master' into docking

Nav: Fixed gamepad/keyboard moving of window affecting contents size incorrectly, sometimes leading to scrollbars appearing during the movement. + minor fix with the mostly dead Ctrl+wheel scaling.

Merge branch 'master' into docking ...

# Conflicts:
#	imgui.cpp
#	imgui_internal.h

Internals: Window rectangles: Renaming of all rectangles toward their final form. Should be a no-op. Renamed GetWorkRectMax() to GetContentRegionMaxAbs(). Metrics shows SizeContents.

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

CollapsingHeader: When a close button is enabled, better clip the label to avoid overlap. (#600)

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

Docking: Saving local _NoResize flag. (#2583)

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

Comments, todo entries, moved ImGuiSelectableFlagsPrivate in higher ranges to match others.

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