Merge branch 'viewport' into docking

# Conflicts:
#	imgui.cpp

docs/CHANGELOG.txt

@@ -125,11 +125,14 @@ Other Changes:
 - InputFloat: When using ImGuiInputTextFlags_ReadOnly the step buttons are disabled. (#2257)
 - Nav: Fixed an keyboard issue where holding Activate/Space for longer than two frames on a button would unnecessary 
   keep the focus on the parent window, which could steal it from newly appearing windows. (#787)
+- Nav: Fixed animated window titles from being updated when displayed in the CTRL+Tab list. (#787)
 - Error recovery: Extraneous/undesired calls to End() are now being caught by an assert in the End() function closer
   to the user call site (instead of being reported in EndFrame). Past the assert, they don't lead to crashes any more. (#1651)
   Missing calls to End(), past the assert, should not lead to crashes or to the fallback Debug window appearing on screen.
   Those changes makes it easier to integrate dear imgui with a scripting language allowing, given asserts are redirected
   into e.g. an error log and stopping the script execution.
+- ImDrawList: Optimized some of the functions for performance of debug builds where non-inline function call cost are non-negligible.
+  (Our test UI scene on VS2015 Debug Win64 with /RTC1 went ~5.9 ms -> ~4.9 ms. In Release same scene stays at ~0.3 ms.)
 - IO: Added BackendPlatformUserData, BackendRendererUserData, BackendLanguageUserData void* for storage use by back-ends.
 - IO: Renamed InputCharacters[], marked internal as was always intended. Please don't access directly, and use AddInputCharacter() instead!
 - IO: AddInputCharacter() goes into a queue which can receive as many characters as needed during the frame. This is useful