Blender Git Loki

Sculpt: Rename Topology Brush to Slide Relax Brush

The full name was "Topology Slide/Relax", but it didn't fit in the
toolbar UI. This was causing some problems:

- The mesh filter that does the same thing is called "Relax"
- We may want to add a "Topology Brush" tool in the future that is more
oriented to retopology task (like creating strips of quads), so by doing
this we avoid having two tools with the same name in the UI.

Reviewed By: billreynish

Differential Revision: https://developer.blender.org/D6590