Feature request: Tx iGate

[mattbk]

To have more complete APRS integration, it would be nice to have to option for packets transmitted from APRS-IS to LoRa. On 2m, this is usually limited to messages addressed to stations expected to be in range of the iGate. Depending on the area and coverage of different types of digipeaters, transmitting all packets within a radius might be useful. This would allow better two-way communication between 2m and LoRa without requiring a crossband digipeater.