Merge branch 'master' into viewport ...

# Conflicts:
#	examples/imgui_impl_sdl.cpp

Examples: Comments about GLFW/SDL versions

Tweaked asserts

Build fix for master.

Merge branch 'master' into viewport ...

# Conflicts:
#	examples/imgui_impl_sdl.cpp

Examples: SDL: Avoid testing for SDL_GetKeyboardFocus() on Android and iOS (like Emscripten). (#421)

Examples: SDL: Fixed compilation for SDL 2..0.3 and less (running on our test servers) and clarified a bit of the messy situation. Followup to 8dd83c5. (#1542, #2117)

Examples: SDL: SDL_GetMouseState() seems problematic, movements feels laggy in the non-viewport code path. (#1542, #2117)

Viewport: Win32, GLFW, SDL: Clarified back-ends by using global mouse position direction. GLFW: disabled io.MouseHoveredViewport setting under Mac/Linux. (#1542, #2117) + various comments.

Fixed typo.

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

Merge branch 'master' into viewport ...

# Conflicts:
#	examples/imgui_impl_dx10.cpp
#	examples/imgui_impl_dx11.cpp
#	examples/imgui_impl_glfw.cpp
#	examples/imgui_impl_opengl2.cpp
#	examples/imgui_impl_opengl3.cpp
#	examples/imgui_impl_sdl.cpp
#	examples/imgui_impl_win32.cpp
#	imgui.h

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

Viewport: imgui_impl_sdl2: Added support for PlatformIO Platform_SetWindowAlpha.

Merge branch 'master' into viewport ...

# Conflicts:
#	examples/imgui_impl_sdl.cpp

Examples: SDL: changed the signature of ImGui_ImplSDL2_ProcessEvent() to use a const SDL_Event*. (#2187)

Viewport: Added support for minimized window which caused problem when ImGuiBackendFlags_HasMouseHoveredViewport was not supported. (#1542) + todo

Examples: SDL: Fixed usage of SDL_GetDisplayDPI (#2137, #1676)

Merge branch 'master' into viewport ...

# Conflicts:
#	examples/imgui_impl_sdl.cpp
#	imgui.cpp

Fix spacing in imgui_imp_sdl example (#2111)

Merge branch 'master' into viewport ...

# Conflicts:
#	examples/imgui_impl_win32.cpp
#	examples/imgui_impl_win32.h
#	imgui.cpp

Examples: Referring to missing gamepad support in back-end that are missing it.

Merge branch 'master' into viewport ...

# Conflicts:
#	examples/imgui_impl_dx9.cpp
#	examples/imgui_impl_opengl2.cpp
#	examples/imgui_impl_opengl3.cpp
#	examples/imgui_impl_vulkan.cpp

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

Examples: Viewport: Disabling swap intervals / vsync on secondary context to match what the DX11 bindings is doing. (#1542)

Merge branch 'master' into viewport ...

# Conflicts:
#	examples/imgui_impl_dx11.cpp
#	examples/imgui_impl_glfw.cpp
#	examples/imgui_impl_sdl.cpp
#	imgui.cpp

imgui_impl_glfw, imgui_impl_sdl: Workaround for Emscripten which doesn't seem to handle focus related calls. (#1941)

Merge branch 'master' into viewport ...

# Conflicts:
#	examples/imgui_impl_sdl.cpp
#	imgui.cpp

Examples: SDL: Removed SDL_HAS_WARP_MOUSE_GLOBAL in the non-viewport branch. (#1954) (+1 squashed commits)

Viewport: Removed the need for the back-end to fill io.MousePosViewport, it seems unnecessary at this point. (#1542)