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]
UE-3850 - AI: BehaviorTree: Pressing enter in search results does not refresh the list as seen in other parts of the editor
[CL 2397418 by Thomas Sarkanen 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]
#add Added UEdGraphNode::GetNodeNativeTitle to return a native title for a node.
#add Added UEdGraphNode::GetNodeSearchTitle to return the native and localized title for a node, together, for searching.
#add Can hold "alt" over a node (in the graph panel, or the palette) to see the native name of the node.
#ttp 331252 - Blueprints: Editor: L10N: Blueprints need to consistently show localized node names and when searching need to search both the localized name and the native name
#codereview justin.sargent
[CL 2044506 by Michael Schoell in Main branch]
