Add TTGO Heltec WiFi LoRa 32 V2 to the well-known boards in GetPinmap_ThisBoard()

[terrillmoore]

We have GetPinmap_ttgo_loraw32_v1(), but it's not automatically picked up.

A review of the docs and the "official" Heltec LMIC indicates that it can use the same pinmap as the TTGO LoRa32 V1, so for now we can just use GetPinmap_ttgo_lora32_v1() for it too.

[terrillmoore]

Changes pushed on https://github.com/mcci-catena/arduino-lmic/tree/issue453 -- if anyone has a chance to test, that branch should work. You'll need to update project config for EU, etc.

[terrillmoore]

Closed properly by #471