Closes #806. Fixed: if a selected row was removed from a table view, the selection remained and would show up again if a new row was later added.

AppKit/CPTableView.j

@@ -1616,11 +1616,11 @@ CPTableViewFirstColumnOnlyAutoresizingStyle = 5;
 
 - (void)noteNumberOfRowsChanged
 {
+    var oldNumberOfRows = _numberOfRows;
+
     _numberOfRows = nil;
     _numberOfRows = [self numberOfRows];
 
-    var oldNumberOfRows = _numberOfRows;
-
     // remove row indexes from the selection if they no longer exist
     var hangingSelections = oldNumberOfRows - _numberOfRows;