Make the Graph Editor Cursor panel fit in and use the split layout.
Also removed the snap buttons, since they were only a subset of the snapping possibilities, all of which are in Key > Snap anyway, and also in the context menu.
Update the theme to use correct hierarchy progression like in other editors.
Differential Revision: https://developer.blender.org/D6785
Reviewed by Brecht van Lommel
11e9ad412e