Compact general purpose extruder

Superceded by http://www.thingiverse.com/thing:59352

I have been using my quikfit compact extruder for many months and prints and finally it blew apart tonight and fortunately I still had a spare but that is my last one and I really need an extruder suitable for hotter temperatures for nylon and ABS so this extruder will use an aluminium plate below the extruder to hold a J-head hot end. The alloy plate will remain solid at higher temperatures and should have better print quality for longer.