Geoff:>fixed issue where Neuron and Connection needed to know about each other
	modified:   Neurons/Brain.cpp
	modified:   Neurons/Brain.h
	modified:   Neurons/Connection.cpp
	modified:   Neurons/Connection.h
	modified:   Neurons/InputNeuron.h
	modified:   Neurons/Neuron.cpp
	modified:   Neurons/Neuron.h
	modified:   Neurons/OutputNeuron.h
	modified:   Neurons/Playground.cpp
	modified:   Neurons/Signal.cpp
	modified:   makefile