GUI: rename roughness class
Prefix "Layer" seems redundant.
Files: LayerRoughnessItems
--> RoughnessItems
Class: LayerBasicRoughnessItem
--> BasicRoughnessItem
Prefix "Layer" seems redundant.
Files: LayerRoughnessItems
--> RoughnessItems
Class: LayerBasicRoughnessItem
--> BasicRoughnessItem