TODO list update + Changelog and comments for #1803.

Moved DragScalar, InputScalar, SliderScalar to imgui.h as well as ImGuiDataType (#320, #643, #708, #1011)

Merge branch 'master' into viewport ...

# Conflicts:
#	examples/imgui_impl_dx9.cpp
#	imgui.cpp
#	imgui.h

Settings: Added LoadIniSettingsFromDisk(), LoadIniSettingsFromMemory(), SaveIniSettingsToDisk(), SaveIniSettingsToMemory(), io.WantSaveIniSettings. (#923, #993)

DragInt: Patch old format strings to replace %f by %d when using the DragInt() entry point. (#320, #643, #708, #1011)

Viewport, Platform: Refresh monitor list (win32, glfw) + avoid calling GetWindowFocus before platform window creation to not require of backend to null-check things inconsistently. (#1542)

Viewport: Removed unnecessary fields (now that the coordinate system is consistent accross viewports): MouseRefPrevViewport, MouseClickedPosViewportId. (#1542)

Viewport, Platform: Using Platform_GetWindowFocus to provide a much stronger heuristic of platform z-order, in replacement for when the back-end cannot provide io.MouseHoveredViewport. The pressure for it to work well increased with the use of viewports by popups/menus. (#1542)

Viewport: Fixed mouse hover flicker on mouse button release frame after moving a window. (#1542) ...

Platform: Clarifying some comments in back-ends.

Viewport, Platform: Fixed IME positioning for multi-viewport. Moved API from ImGuiIO to ImGuiPlatformIO. Because it is extremely unlikely to people redefined this API manually the moving-forward-breakage is ok. (#1542) ...

SDL2 ime support under Win32 never worked properly because of SDL interferences.

Viewport: Clamp windows within monitors + fallback rescue window when it is out of sight (e.g. removed monitor, changed resolution) + Win32: declare primary monitor at the beginning of the list. (#1542)

Viewports: Todos, Tooltips/menus not automatically forced into their own viewport when the NoMerge flag is set (however the multiplication of viewports makes them more likely to protude and create their own). Win32: try to make primary monitor the first tin the list. (#1542)

Documentation bits. Misc comments.

Comments about io.WantCapture flags + todo entries.

Demo: Added more complete Combo demo. (#1658)

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

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

Misc comments, todos + reintroduced removed ImGuiCol defines under !IMGUI_DISABLE_OBSOLETE_FUNCTIONS wrap.

Font: Fixed MergeMode adding duplicate glyphs data instead of reusing existing (broken by 072d6d8)

Nav: Comments, guides.

Nav: SetItemDefaultFocus() doesn't make the navigation cursorr highlight visible. Renamed NavInitResultExplicit to NavInitRequestFromMove. (#787)

Nav: Comments (#787)

Nav: Child window is restored on focus when returning to layer 0 or refocusing. This is a little experimental and potentially error-prone right now. (#787, vaguely relate to ~#727) Ideally we should maintain a non-sorted last-focused list that include childs windows.

Nav: Tweak code to be easier to follow + updated todo list after clarifying an issue.

Merge branch 'master' into navigation

Moved extra_fonts/ to misc/fonts/. Moved .natvis file to misc/natvis/ (#1569)

Nav: Updated TODO list.

Nav: workaround to kindly handle ALT-TAB without detecting TAB-release on backends that clear all keys on unfocus. (#787)

Merge branch 'master' into navigation

Nav: Keyboard: Added CTRL+TAB (and CTRL+Shift+TAB) style window selection. (#787)