Support of feedback SMS

[Robert-Faltus]

Note:
This applies to GSM modules which are officialy supported by Adeon library (eg. SimCOM modules).

Description:
Add support for sending status info via SMS after receiving of the Adeon command or phone call with sendFeedback(char* msg). This status info should be sent to sender/caller only if the sender is authorized with ADEON_ADMIN or ADEON_USER user rights (ADEON_HOST excluded).

Example of status info:

• Command accepted.
• Command declined – user is not authorized.
• Command declined – wrong format.
• Drop-call accepted.
• Drop-call declined.

[vzahradnik]

Instead of implementing this feature here, I suggest to spend some time improving the TinyGSM library, and integrate Adeon there. This library is well-tested. The only major thing it is lacking is the support for receiving SMS messages.