v1.7.1

ProtoHydra 1.7.1

Serial console hardening.

Fixes: pulling the adapter put the read loop into a busy loop instead of
reporting the disconnect; reconnecting straight after disconnecting
failed on our own handle that the driver had not released yet; a device
dumping binary could grow the CSI parameter list without bound, print C1
controls into the grid and leave the parser stuck in a half-written
sequence.

The modem line poll now reports a lost device, and the port list is
rescanned afterwards because Windows can hand a replugged adapter a
different COM number.