Pull updates to ReadMe

Set default alphabet for sendSMS

ReadMe Update from vshymanskyy

XBee updates, other tweeks

problem was new lines, not time.

Otherwise was going into an endless reading loop because user code only asked for a short part of the total amount of data sent.

Added (sub)module switches
Added PIN define and SIM readiness check
Modified GPS to use TINY_GSM_HAS_GPS - more modules has GPS now, will alter header files in another change

Is there a way to force it to return in smaller chunks?

Also fixed the "isNetworkConnected" for ESP8266

Also shorted time between checks in "isNetworkConnected" for all modems