Throws a pts critical exception if the expected bitstream file is missing.

The used kernel cp210x module was probablly a hacked version.
Now using the official source from Silicon Labs.
The kernel module sources are in the usb-relay-box1 project.

test07: Change min value from -32768 to -32767, due to variable saturation block (-> symetric saturation).

- nb. remaining shots
- sampling frequency
- internal trigger test mode
- internal trigger threshold filter
- variable saturation (set to max at init)

-> fmc_eic and timetag core moved to mezzanine (behind bridge).
-> ddr addr and data (for svec) moved.

fmc_adc, many tests: Add sdb to fmc_adc class, use csr class for timetags reading, change trigger position to byte address (was sample address).