Viewport: Comments about honoring ImGuiViewportFlags_NoInputs and MouseHoveredViewport. (#1542)

Viewport: Renamed RenderPlatformWindows() to RenderPlatformWindowsDefault(), tweaked examples and emphasis optional Viewport code path. (#1542)

Merge branch 'master' into viewport ...

# Conflicts:
#	examples/imgui_impl_dx10.cpp
#	examples/imgui_impl_dx11.cpp
#	examples/imgui_impl_dx12.cpp
#	examples/imgui_impl_dx9.cpp
#	examples/opengl2_example/imgui_impl_glfw_gl2.cpp
#	examples/opengl3_example/imgui_impl_glfw_gl3.cpp
#	examples/sdl_opengl2_example/imgui_impl_sdl_gl2.cpp
#	examples/sdl_opengl2_example/imgui_impl_sdl_gl2.h
#	examples/sdl_opengl3_example/imgui_impl_sdl_gl3.cpp
#	examples/sdl_opengl3_example/imgui_impl_sdl_gl3.h
#	imgui.cpp

Added extra comments and assertions to avoid user combining ImGuiCond flags. (#1694)

Tooltip windows uses PopupBorderSize (#1697) + commented out debug stuff.

Viewport: Moved OverlayDrawList to be a per-viewport instead of being global + fix overlay clipping glitch during viewport creation frame + support for software mouse cursor stradding over multiple viewport. The overlay draw list move is rather important as draw lists are not shared among viewports anymore and we can do a swap of their data without copying it. (#1542)

Added InputDouble() function. We use a format string instead of a decimal_precision parameter to also for "%e" and variants. (#1011) May transition the other InputXXX function to use format strings as well.

InputFloat: Scientific input. InputText: Added ImGuiInputTextFlags_CharsScientific to add 'e' 'E' to list of characters that can be input. (later useful for #1011)

Merge branch 'master' into viewport ...

# Conflicts:
#	examples/imgui_impl_dx10.cpp
#	examples/imgui_impl_dx11.cpp
#	examples/imgui_impl_dx12.cpp
#	examples/imgui_impl_dx9.cpp
#	examples/opengl2_example/imgui_impl_glfw_gl2.cpp
#	examples/opengl3_example/imgui_impl_glfw_gl3.cpp
#	examples/sdl_opengl2_example/imgui_impl_sdl_gl2.cpp
#	examples/sdl_opengl3_example/imgui_impl_sdl_gl3.cpp
#	examples/vulkan_example/imgui_impl_glfw_vulkan.cpp
#	imgui.h

IO: Added ImGuiConfigFlags_NoSetMouseCursors. Added ImGuiBackendFlags_HasMouseCursors, ImGuiBackendFlags_HasSetMousePos. (#787, #1495, #1202)

Added ImGuiBackendFlags for backend to expose its capabilities. Added ImGuiBackendFlags_HasGamepad. (#787, #1542)

IO: Renamed io.WantMoveMouse to io.WantSetMousePos (was added in 1.52, _not_ used by core and only honored by some binding ahead of merging the Nav branch) + internal renaming (#787)

Merge branch 'master' into viewport ...

# Conflicts:
#	examples/sdl_opengl2_example/main.cpp
#	examples/sdl_opengl3_example/main.cpp
#	examples/vulkan_example/main.cpp

ImVector: Fixed insert() helper using the = operator (followup to be consistent with 4186c2c)

Viewport, Platform: Added void* to render/swap buffer functions. Comments. (#1542, #1042)

Nav: Track nav input source more generally (gamepad vs keyboard) (#787) + update todos and demo tweaks

Viewport, Platform: Refactored platform interface. Removed need to use imgui_internal.h in backends. Split viewport into public facing ImGuiViewport and internal structure. Exposing enough data to provide custom tweaked renderers. Renamed handlers, fixed lots of inconsistencies. (#1542, #1042)

Merge branch 'master' into viewport ...

# Conflicts:
#	imgui.h

imgui.h: Various comments and tweaks.

imgui.h: Moved columns lower in the file. Various spacing changes and minor comments.

Merge branch 'master' into viewport ...

# Conflicts:
#	imgui.h

ImVector: Added copy/assign operators as helpers to ease cloning of data.

ImDrawList: Added Clone() helper function.

ImVector: resize() / push_back() use memcpy() as we are not supposed to be constructor/destructor/operator aware at all. (If we do need to rework ImVector). In turn this will allow us to define assign/copy operators.

ImVector: Using value_type consistently. Spacing.

Update TODO list, minor fix in Readme, comments, Clang -Weverything warning fix in imgui_draw.cpp under Windows.

Examples: SDL,GLFW,Vulkan: The Platform<>Renderer link is handled by SDL/GLFW platforms, both can compile without Vulkan headers, SDL+Vulkan is now on part with GLFW+Vulkan (aka broken the same way!). (#1542)

Viewport: Fixed software mouse cursor from appearing in all multiple lists simultaneously. (#1542)

Viewport: Obsoleted io.DisplayPos (which was a Viewport branch thing), added ImDrawData::DisplayPos, DisplaySize (#1542) wip

Merge branch 'master' into viewport