* BIG refactor: 'board' and 'radio' objects now defined in 'target.h/.cpp'

* mesh::RTCClock class moved to MeshCore.h

variants/lilygo_tlora_v2_1/target.cpp

@@ -0,0 +1,25 @@
+#include <Arduino.h>
+#include "target.h"
+
+LilyGoTLoraBoard board;
+
+static SPIClass spi;
+RADIO_CLASS radio = new Module(P_LORA_NSS, P_LORA_DIO_0, P_LORA_RESET, P_LORA_DIO_1, spi);
+
+#ifndef LORA_CR
+  #define LORA_CR      5
+#endif
+
+bool radio_init() {
+  spi.begin(P_LORA_SCLK, P_LORA_MISO, P_LORA_MOSI);
+  int status = radio.begin(LORA_FREQ, LORA_BW, LORA_SF, LORA_CR, RADIOLIB_SX126X_SYNC_WORD_PRIVATE, LORA_TX_POWER, 8);
+  if (status != RADIOLIB_ERR_NONE) {
+    Serial.print("ERROR: radio init failed: ");
+    Serial.println(status);
+    return false;  // fail
+  }
+
+  radio.setCRC(1);
+  
+  return true;  // success
+}