Breaking changes include:
* Rename of GEditorModeTools -> GLevelEditorModeTools to signify that it applies only to the level editor modes
* Addition of FEditorModeRegistry, responsible for managing and creating new editor modes. Modes are no longer registered with an instance of the mode, instead with a mode factory that is able to create a new mode of that type.
* Editor modes now operate on FEditorViewportClients rather than FLevelEditorViewportClients
* Added ability to specify an FEditorModeTools when creating an FEditorViewport
Moved component vizualiser manager handling outside of individual editor modes, and into FLevelEditorViewportClient. This should make it easier to transplant in future.
This work addresses TTP#334640 - EDITOR: Investigate making editor modes a per-'editor' concept
Reviewed by Michael Noland, Matt Kuhlenschmidt
[CL 2109245 by Andrew Rodham in Main branch]
#ttp 333422 BSP does not update when editing from a 2d viewport.
#proj Editor
#branch UE4
reviewed by Thomas.Sarkanen
[CL 2057814 by Andrew Copland in Main branch]
#summary Fixed not being able to set camera movement speed in toolkit viewports
#change Moved anything to do with camera speed in the level editor viewport settings into the level editor viewport client and added a transient camera speed setting to all other viewports.
#proj Editor
#branch UE4
#reviewedby Thomas.Sarkanen, Matt.Kuhlenschmidt
[CL 2054156 by Andrew Rodham in Main branch]
