improved 7-segment display decoding

now decodes alpha characters the firmware might display on the
7-segment display, e.g. error messages from section 3-22 of manual
use 5370B firmware by default

switch to using the 5370B firmware for all builds since it seems
backward compatible with 5370A instruments
random fixes

various bug fixes and debugging improvements
new daemon scripts

scripts for starting a 5370 daemon at boot time (not fully working yet)
allow ROM refs with bit 15 set

handle PHK's discovery that the 5370B std dev firmware accesses a table
in the ROM with bit 15 set