Update region_ops.txt to match current behaviour, and fix a couple of comments.

Update region_ops.txt to better describe the current behaviour of
Editor::get_regions_from_selection_and_edit_point(), and fix a couple of
comments that still referred to the no-longer-existing 'edit' property of
route groups.

doc/region_ops.txt

@@ -24,9 +24,8 @@ If the edit point is `mouse':
      if the mouse is over a selected region, or no region, this method returns all selected regions.
      if the mouse is over an unselected region, just that region is returned.
 
-For other edit points the method returns the selected regions AND those that are both under the edit position
-AND on a selected track, or on a track which is in the same active edit-enabled route group as a selected
-region.
+For other edit points the method returns the selected regions. If no regions are selected, it returns 
+the regions under the edit position on the selected tracks.
 
 The action handlers call the appropriate method to decide which regions to operate on.
 

gtk2_ardour/editor.cc

@@ -4037,7 +4037,7 @@ Editor::restore_editing_space ()
 
 /**
  *  Make new playlists for a given track and also any others that belong
- *  to the same active route group with the `edit' property.
+ *  to the same active route group with the `select' property.
  *  @param v Track.
  */
 
@@ -4053,7 +4053,7 @@ Editor::new_playlists (TimeAxisView* v)
 
 /**
  *  Use a copy of the current playlist for a given track and also any others that belong
- *  to the same active route group with the `edit' property.
+ *  to the same active route group with the `select' property.
  *  @param v Track.
  */
 
@@ -4068,7 +4068,7 @@ Editor::copy_playlists (TimeAxisView* v)
 }
 
 /** Clear the current playlist for a given track and also any others that belong
- *  to the same active route group with the `edit' property.
+ *  to the same active route group with the `select' property.
  *  @param v Track.
  */