Fixes, Style stuff and Feature enhancements:

[Apollon77]

• reworked modem initialization that order of commands is correct after PIN

• add support to check and provide a PIN

• added an optional logger via options; currently supports "debug" logging

• added debug logging for Writes and Received commands

• added a custom initialization command (some modes need that) which is then send after PIN check

• added options.incomingSMSIndication flag to officially send enable command for push info on new messages; default is true for backward compatibility

• changed double-quotes into single quotes in strings

• send AT+CMEE=1 (enhanced error infos) and CREG=2 (enhanced details on CREG command)

• make some checks more generic

• add error details to the error messages

• some code and logic error from last refactoring (was not really working on some places?) are fixed

• add signalStrength property with calculated db value on Signal-Strength method

• add proper error handling when accessing empty SMS slots

• executeCommand always need to return an object, else all the "item.logic" calls will end in an exception

• removed unneeded comma in some objects

• fix checkSimMemory

• rename introduced "checkModem" to "resetModem" because ATZ will also reset to factory defaults!

• add a new checkModem to only send AT to check communication with device

• parse SimInbox response synchronous to prevent pot. async problems (in fact now method can do both, the event is emitted async)

• fixes #18, #19

• partially #20

[Apollon77]

Requesting review @karianpour, @zabsalahid

[Apollon77]

One note: I'm not able to get "Incoming SMS or Call notifies", but It may be my device ... so please check that carefully on your side too