Get a build kind of working.

Segfaults at:

```
$ ./bin/gqgmc /dev/gqgmc
/dev/gqgmc
USB is opened

date: 030513
time: 171730
get version
GMC-300Re 4.18

get serial number
Paused: to continue, press ENTER..
f48800d1052677

get CPM
Paused: to continue, press ENTER..
11

get 5 samples of CPS
Paused: to continue, press ENTER..
1
1
1
0
0
get battery voltage
Paused: to continue, press ENTER..

Get a build kind of working.
4.2V

Turning on auto-CPS data
Paused: to continue, press ENTER..
s=0 0
s=1 2
s=2 0
s=3 0
s=4 0
s=5 0
s=6 1
s=7 0
s=8 1
s=9 0
turning off CPS
get history
Paused: to continue, press ENTER..
zsh: segmentation fault (core dumped)  ./bin/gqgmc /dev/gqgmc
```