refactored tga code to allows use outside of EditorFactories.cpp
added support for grayscale jpeg
fix memory leak in jpeg code
changes in AssetTools to allow to specify precise factory when multiple factories support the same filetype
changes in Plugin.cs to allow binary only plugins
exposed parts of engine API to other modules
[CL 2108453 by Matt Kuhlenschmidt in Main branch]
#TTP 331892 - Editor: Blueprint Defaults Diff: Lauching diff tool does not work with spaces in paths
#branch UE4
#proj Editor.BehaviourTreeEditor
#proj Editor.WorldBrowser
#proj Editor.Levels
#proj Developer.AssetTool
#change Wrapped the file paths in double quotes, this means that the full path gets passed to P4Merge
#reviewedby Chris.Wood
[CL 2060955 by Barnabas McManners in Main branch]
#ttp 333671 - EDITOR: Content Browser: Customizable shortcut for opening assets and folders
#branch UE4
#add Added two new commands so that the Enter and SpaceBar functionality can be remapped.
#change Renamed EAssetTypeActivationMethod types so they don't mention which key was used, but the action that key performed.
reviewed by Thomas.Sarkanen
[CL 2059964 by Andrew Brown in Main branch]
* Porting a large swath of the code from SlateComponentWrapper into UMG.
* Creating a derived UBlueprint for AUserWidget. (The base class for a UMG widget).
[CL 2050095 by Nick Darnell in Main branch]