Add support for AX.25 frame decoding

[bng919]

Received packets are displayed in hexadecimal format containing the raw data received. It would be useful to have the ability to decode the call sign's and data fields according to the AX.25 specifications: AX.25.2.2.pdf

This would be best done in DecoderDireWolf#startDecoder() before primArr is added to decodeData:

agsc/src/main/java/decode/DecoderDireWolf.java

Lines 112 to 118 in cb7b7ca

	// Convert Byte[] to byte[] (primitive type)
	byte[] primArr = new byte[arr.length];
	for (int i = 0; i < primArr.length; i++) {
	primArr[i] = arr[i];
	}
	decodedData.add(primArr);
	Log.info("Received packet:\n" + HexadecimalUtils.hexDump(primArr));

A field in config.properties should be created to allow the user to turn on/off AX.25 decoding.