gmoledina/GMGridView — pull request #47 by Bringo (2012-02-11 20:54:56+00:00)
Title: sortingDelegate additions: allow/disallow movement and insertion of items at certain index

Extended the sortingDelegate with two more optional delegate methods:

`- (BOOL)GMGridView:(GMGridView *)gridView shouldAllowMovingCell:(GMGridViewCell *)view atIndex:(NSInteger)index;` is called when a move is about to start. If this method returns `NO`, the move won't take place.

`- (BOOL)GMGridView:(GMGridView *)gridView shouldAllowMovingCell:(GMGridViewCell *)view toIndex:(NSInteger)index;` is called when an item is moved to a new position in the grid. If this method returns `NO`, the insertion won't take place.