Fixed a bug in the enumeration of USB devices. This seems to make it
possible to use the libftd2xx-1.0.4 version for digital testboards.
Merge remote branch 'origin/devel-DTB' into devel-DTB
Merge branch 'devel-DTB' of https://github.com/mrossini-ethz/psi46expert into devel-DTB

Conflicts:
	src/BasePixel/usb.cpp