Support uploading settings

[buxtronix]

The USB protocol supports uploading settings to the device. This should be implemented.

Some info on the protocol:

0f - start
05 - length
11 - command
00 - set charge cycle parameters
00 - ??
0a - charge-disch wait (mins) (max 60)
1b - cksum
ff - end
ff - end

0f - start
07 - length
11 - command
01 - set time limits
00 -
00 - time limit en
00 - time limit mins
b4 - time limit mins
c6 - cksum
ff - end
ff - end

0f - start
07 - length
11 - command
02 - set capacity limits
00 - 
00 - cap limit enable
1f - caplimit
40 - caplimit
72 - cksum
ff - end
ff end

0f - start
06 - length
11 - command
03 - set buzzer param
00 - 
01 - key buzz
01 - sys buzz
16 - cksum
ff - end
ff - end

0f - start
05 - length
11 - command
05 - set temp limit
00 -
50 - templimit
66 - cksum
ff - end
ff - end