UETOOL-213 - Minimize Slate FString -> FText conversion (remove SLATE_TEXT_ATTRIBUTE)
This fixes any editor/engine specific code that was passing text to Slate as FString rather than FText.
[CL 2399803 by Jamie Dale in Main branch]
* Moved Slate.h into SlateBasics.h and began shifting less commonly used headers into SlateExtras.h.
* Slate.h now simply includes SlateBasics.h and SlateExtras.h.
* Slate.h includes a deprecated warning now to indicate that SlateBasics.h + specific includes should be used instead.
* Moved dozens of inlined functions using Slate widgets into .cpp files to avoid header dependencies.
* All code samples now include SlateBasics.h and SlateExtras.h so future shifts will not break most those projects, but not trigger the deprecation warning of including Slate.h.
#BUN
[CL 2329610 by Wes Hunt in Main branch]
Automation: Milestone 3 and fixes for milestone 2
-Added new EditorShot command to take editor screenshots
-Made the ExterialTool options use the dierctory picker
-Fixed a bug with the StaticMeshEditor test if the tutorial pops up
-StaticMeshUV test now uses async package loading
-Added a display every Nth screenshot to the screenshot compre tab
-Added support to disable screenshots or request full size ones
-Changed the screenshots so they save to the game directory even if you run the frontend by itself
-Added screenshot support for the load all maps tests
[CL 2071712 by kevin hamilton in Main branch]
