AVR Dragon - solid enclosure

Enclosure for AVR Dragon programmer and debugger.

Design notes:
* The enclosure should not press any components mounted on the Dragons PCB; there are separators (placed on the top part of the enclosure) to ensure that the ferm contact stays only between enclosure and PCB;
* Allows space for connecting IDC cables, not just jumper wires;
* The foam from the original package can be used to safely secure the PCB inside the enclosure without directly applying presure to the board when tightening the screws to connect the two parts of the case;
* Only VCC, GND, ISP/PDI and JTAG headers are exposed; that is, the enclosure does not expuse HV programming header or the headers supporting the ZIF socket;
* The two parts of the enclosures are connected via 4 x M2 screws & nuts; however, these are optional as the enclosure can be assembled ony by fitting the bottom part inside the top part of the case.

Printing hint:
The enclosure is easy to print and easy to assemble; however, pl