Additional region commands

* SceneManager - additional commands
  - "show objects" - Display a list of objects in the currently
selected scene
  - "resize object" - Change the scale of a named object
  - "rotate region" - Rotates ( 2D, x,y only) all region objects around
a center point (default center of region)
  - "scale region" - Scales all region objects by the specified amount
  - "reposition region" - Move region objects by the specified amounts
(x,y,z) (Alternative to 'offset region prims')
  - "clear region" - Clear the region of objects leaving the current
terrain

* TerrainChannel
  - Additional helper functions