Fixing it lest if gets copied and lives on elsewhere. Note that it may
still be necessary to add a small negative correction (in the order of
-0.1 mm) to compensate for deflection of the workpiece.
- c2usb/cam/pcb.pl ($d): there are 25.4 mm in an inch, not 2.54
- c2usb/cam/pcb.pl ($d): the endmill used has a diameter of 35 mil, not
8 mil
- c2usb/cam/pcb.p ($r): don't apply correction for imagined mechanical
issues (now what we're working with correct values)