Blender Git Loki

Cycles: Make UI for subdivision more clear

Users have been getting a bit confused by the way things are worded/arranged in
the UI. This patch makes a few changes to the UI to make it more clear how to
use subdivision:

- make Subdivide UVs option inactive when adaptive subdivision is enabled as UV
subdivision is currently unsupported
- add "px" to dicing rates in the Geometry Panel
- display the final dicing rate in the modifier
- reworded "Dicing Rate" in the modifier to "Dicing Scale" to make more clear
that this is a multiplier for the scene dicing rate and added a note the the
tooltip pointing the user to that setting in the Geometry Panel

Reviewed By: brecht

Differential Revision: https://developer.blender.org/D2174