Split X-Ends for Prusa i3 - plus option for cableties

There was really not much to improve.
Really love the design of enif http://www.thingiverse.com/thing:514582

The Idler-Side of one printer broke. Tried to fix it during the print but it was impossible. I taped the broken Z-Carriage while printing, designed the cabletie-gaps and with the last stroke of the printer I managed to get them out :-)