Optimisation: LoRa E5 channel selection AT command

[mcauser]

I noticed on these two lines:
https://github.com/disk91/WioLoRaWANFieldTester/blob/master/LoRaComE5.cpp#L273
https://github.com/disk91/WioLoRaWANFieldTester/blob/master/LoRaComE5.cpp#L344

They are looping over all 72 channels and calling AT+CH=chn,OFF to disable channels.

An alternate way of doing it (in a single AT command) is by calling AT+CH=NUM, from-to, eg AT+CH=NUM, 8-15.
This enables 8-15 and disables all other channels.

7x less AT commands isn't going to make a huge difference, but every bit helps.

Page 31 in LoRa E5 AT Command specs v1.0 pdf:

[disk91]

Thank you for the proposal, good idea, I'll consider this in a future release