Addendum to #2635. Add support for multi-viewports in SDL+DX!! example. making all Win32-centric back-ends handle PlatformHandleRaw. Using the field to use/store the HWND for internal purpose in SDL/GLFW back-ends. (#1542)

Viewport: Added PlatformHandleRaw. Update SDL+DX11 example. (#1542, #2635)

Merge branch 'master' into docking ...

# Conflicts:
#	docs/CHANGELOG.txt

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

Removed redirecting functions/enums that were obsoleted in version 1.51 (June 2017): ImGuiCol_Column*, ImGuiSetCond_*, IsItemHoveredRect(), IsPosHoveringAnyWindow(), IsMouseHoveringAnyWindow(), IsMouseHoveringWindow(), IMGUI_ONCE_UPON_A_FRAME.

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

ImDrawListSplitter: Don't merge draw commands when crossing a VtxOffset boundary + Renamed fields ImDrawChannels to consistently suggest those are internal structures.

ImDrawListSplitter: Fix idx offset when merging (cef88f6) (#2591)

Merge branch 'master' into docking ...

# Conflicts:
#	examples/example_apple_opengl2/main.mm
#	examples/example_emscripten/main.cpp
#	examples/example_glfw_opengl2/main.cpp
#	examples/example_glfw_opengl3/main.cpp
#	examples/example_glfw_vulkan/main.cpp
#	examples/example_glut_opengl2/main.cpp
#	examples/example_sdl_opengl2/main.cpp
#	examples/example_sdl_opengl3/main.cpp
#	examples/example_sdl_vulkan/main.cpp
#	examples/example_win32_directx10/main.cpp
#	examples/example_win32_directx11/main.cpp
#	examples/example_win32_directx12/main.cpp
#	examples/example_win32_directx9/main.cpp
#	examples/imgui_impl_glfw.cpp
#	examples/imgui_impl_sdl.cpp
#	imgui.cpp
#	imgui_widgets.cpp

ImDrawCallback: Allow to override the signature of ImDrawCallback by #define-ing it. This is meant to facilitate custom rendering back-ends passing local render-specific data to the draw callback.

Revert "Changed syntax for (very rarely used) IMGUI_OVERRIDE_DRAWVERT_STRUCT_LAYOUT mechanism, instead you only need to '#define ImDrawVert MyDrawVert' to use this feature, avoiding the need to declare the entire structure within an awkward macro. Using the old macro will now error with a message pointing you to the new method. (#38, #103, #1172, #1231, #2489)" ...

This reverts commit 597c024.

Changed syntax for (very rarely used) IMGUI_OVERRIDE_DRAWVERT_STRUCT_LAYOUT mechanism, instead you only need to '#define ImDrawVert MyDrawVert' to use this feature, avoiding the need to declare the entire structure within an awkward macro. Using the old macro will now error with a message pointing you to the new method. (#38, #103, #1172, #1231, #2489)

Merge branch 'master' into docking ...

# Conflicts:
#	imgui.cpp
#	imgui_internal.h

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.

Comments about obsoleted features version. Todo. Clarify tab bar initial offset (useful if we decide to remove the half-windowpadding clip margin).

Comments (#2599). Moved branch Changelog above 1.71 wip one. Added some missing changelog bits.

Merge branch 'master' into docking

ImDrawListSplitter: extracted out of ImDrawList. Down the line we may obsolete the ImDrawList functions and encourage users to store the splitter aside, in the meanwhile ImDrawList holds a splitter. ...

(This will allow columns/table to recurse.)

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.

Fonts: Added some details about using custom colorful icons.

Docking: Saving local _NoResize flag. (#2583)

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