these devices need no reading USB-in-USB acknowledgement after each command.
To achieve that, proto_flags are passed down to low-level functions. These
flags are taken from device descriptions
hp5590: fixed up get_status command - index should be 0x00, not 0x20
hp5590: bump up the backend version
- Updated the list of supported devices (HP 5500C which is similar to
4570C, 5500C which is similar to 4500C) - only strings/comments, no
code was changed
- Updated backend version
- Updated man page