Added libeladdnode and libelchangefreq packet classes and made tests for them in the test class.

	modified:   SerialCom/makefile
	modified:   SerialCom/packet_test.cpp
	modified:   SerialCom/packets/incomingpacket.cpp
	modified:   SerialCom/packets/incomingpacket.h
	modified:   SerialCom/packets/libeladdnodepacket.cpp
	modified:   SerialCom/packets/libeladdnodepacket.h
	new file:   SerialCom/packets/libelchangefreqpacket.cpp
	new file:   SerialCom/packets/libelchangefreqpacket.h
	modified:   SerialCom/packets/libeliopacket.cpp
	modified:   SerialCom/packets/libeliopacket.h
	modified:   SerialCom/packets/outgoingpacket.cpp
	modified:   SerialCom/packets/outgoingpacket.h
	modified:   SerialCom/packets/receivepacket.cpp
	modified:   SerialCom/packets/receivepacket.h
	modified:   SerialCom/packets/transmitrequestpacket.cpp
	modified:   SerialCom/packets/transmitrequestpacket.h
	modified:   errors.h