Add battery voltage reading to web UI, apply fixed VBAT multiplier, closes #3

source/config.h

@@ -114,8 +114,9 @@ struct __attribute__((packed)) TelemetryPacket {
   uint16_t recalCount;      // [20]
   uint8_t  chargeStatus;    // [22]
   uint8_t  _pad;            // [23]
+  float    battVoltage;     // [24]  raw battery voltage (V)
 };
-static_assert(sizeof(TelemetryPacket) == 24, "TelemetryPacket must be 24 bytes");
+static_assert(sizeof(TelemetryPacket) == 28, "TelemetryPacket must be 28 bytes");
 extern TelemetryPacket telem;
 #endif