Brought back Outliner operations!

Since clicking on outliner items activates/selects, and not all outliner
elements allow selection (like scene, mesh, material, etc) there's another
selection method needed.

It works by leftclicking (click-drag works too) outside of the outliner
icons or texts. This allows rapid selecting, without any change in the
other windows.

Then press Wkey or RightMouse for an operations menu. Based on the
selection you get a menu with options. Currently available;

- Objects: Select/Deselect/Delete
- Materials: Unlink
- Textures: Unlink
- Bones: Select/Deselect/Hide/Unhide

Notes:
- mixed selections give an error.
- selection doesn't flush down into closed outliner items.
- selection state is persistant (saved in files), and unique per
  Outliner window, so can be used as sortof temporal grouping.

Hotkey SHIFT+A: select/deselect all open outliner items

The system can be easily expanded with a lot of interesting options, of
course.

source/blender/src/space.c

@@ -3974,14 +3974,17 @@ static void winqreadoopsspace(ScrArea *sa, void *spacedata, BWinEvent *evt)
 			view2dmove(event);	/* in drawipo.c */
 			break;
 		case RIGHTMOUSE:
-			// outliner_select(sa);
+			outliner_operation_menu(sa);
 			break;
 			
 		case AKEY:
-			outliner_toggle_visible(sa);
+			if(G.qual==LR_SHIFTKEY)
+				outliner_toggle_selected(sa);
+			else
+				outliner_toggle_visible(sa);
 			break;
 		case WKEY:
-			// outliner_operation_menu(sa);
+			outliner_operation_menu(sa);
 			break;
 			
 		case HOMEKEY: