Method send_at_cmd_pretty for LTE class

[rskoniec]

@Xykon, @iwahdan I wonder if you could add (or maybe even replace send_at_cmd) method send_at_cmd_pretty in the LTE class? IMHO it would be very helpful.

[rskoniec]

@robert-hh I thought so. Thanks.

[robert-hh]

@rskoniec NAK. It's good as it is. Keep all the raw information of the lower class and leave polishing to the wrappers.