m1/case/: added rear panel with JTAG hole

m1/case/README

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+Reengineered M1 case parts
+==========================
+
+case.fpd contains an fped-based design of the front and rear panel.
+The geometry is based on
+http://projects.qi-hardware.com/index.php/p/m1/source/tree/master/cad/protocase_v7_laser.dxf
+by Joachim Steiger.
+
+This design is fully parametrized and contains the following changes:
+
+- the holes for the USB sockets are raised by 1.4 mm, for the M1pre-rc4
+  prototype (parameter Iusby):
+  http://en.qi-hardware.com/wiki/File:M1pre-rc4-u-A022.JPG
+
+- additional hole in the rear panel for a mini-USB cable going to
+  the JTAG board (parameters Idbgx and Idbgy, with frame "debug")
+
+Known issues:
+
+- button holes are a bit too tight
+
+- DC connector hole is too tight on all sides