Annular Cooling for Ultimaker

Note that this part has been superseded by V2 (http://www.thingiverse.com/thing:124237)
This is a replacement annular cooling for the Ultimaker nozzle. The original cooling shroud, although functional, can sometimes be counterproductive. The unidirectional nature of the cooling stream can sometimes lift the first layer, especially when printing on a raft. The annular cooling nozzle is aimed at the printed object from all directions, thus cancelling any possible lift.