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.

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)

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

Examples/Backends: DirectX9/10/11/12, Vulkan, OpenGL3 (Desktop GL only): Added support for large meshes (64k+ vertices) with 16-bits indices, enable 'ImGuiBackendFlags_HasVtxOffset' config flag in back-end. (#2591)

Examples: DirectX9/10/11: Taking reference to device + subsequent merge of this in docking will fix DX9 issue #2524

Examples: Added missing per-renderer local changelogs. (#2037, #1639, #2452)

ImDrawCallback_ResetRenderState, Examples: Added support for reset render state callback. (#2037, #1639, #2452)

Examples: DirectX9: Fixed erroneous assert in ImGui_ImplDX9_InvalidateDeviceObjects(). FreeType: Fixed suggested code to not require an initial build call.. (#2454)

ImDrawData: Added FramebufferScale field (currently a copy of the value from io.DisplayFramebufferScale). ...

This is to allow render functions being written without pulling any data from ImGuiIO, allowing incoming multi-viewport feature to behave on Retina display and with multiple displays. If you are not using a custom binding, please update your render function code ahead of time, and use draw_data->FramebufferScale instead of io.DisplayFramebufferScale. (#2306, #1676)
Examples: Metal, OpenGL2, OpenGL3: Fixed offsetting of clipping rectangle with ImDrawData::DisplayPos != (0,0) when the display frame-buffer scale scale is not (1,1). While this doesn't make a difference when using master branch, this is effectively fixing support for multi-viewport with Mac Retina Displays on those examples. (#2306) Also using ImDrawData::FramebufferScale instead of io.DisplayFramebufferScale.
Examples: Clarified the use the ImDrawData::DisplayPos to offset clipping rectangles.

Examples: DirectX9: Fix Clang warning.

Removed trailing spaces (#2038, #2299)

Examples: DirectX9: Explicitly disable fog (D3DRS_FOGENABLE) before drawing in case user state has it set. (#2288, #2290)

About, IO: Added io.BackendPlatformName, io.BackendRendererName for informational/QA purpose.

Examples: Using "dear imgui" terminology in all examples headers/comments + fix minor typo.

Examples: Cast to ImTextureID instead of void* when assigning to TexId. Applied to all examples. (#2015)

Examples: Comments, bits of documentation

Examples: Comments to make ImGuiConfigFlags_NoMouseCursorChange more visible (#1027). + Allegro5: Added support for ImGuiConfigFlags_NoMouseCursorChange flag.

Big example binding refactor (manually imported from Viewport branch, stripped out of Viewport code). (#1870) ...

Read examples/README.txt for some details.
ImDrawData: Added DisplayPos, DisplaySize fields honored by all backends (not strictly necessary to honor just now, but doing it to be ahead)