Ublox GPS Module Case

This is a small case I made for the the GPS receiver base on a Ublox NEO-6M, as shipped by [Unmanned Tech](http://www.unmannedtech.co.uk) in the UK.
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Update 11/08/2014: Added a bit more space around the parts to allow for slight over-printing problems stopping the lid from attaching. Added an option to create four holes in the base to allow for fixing to a quad. There is now also a configurable parameter ```tolerance```, which is a distance that will be added between the lid and the base