Remove backpropagation support from neurons

[stiber]

While remnants of this aspirational code still exist, it has never been used or tested and we have no immediate plans for it.

Graphitti/Simulator/Vertices/Neuro/AllLIFNeurons_d.cpp

Lines 148 to 176 in d22f59d

	if (fAllowBackPropagation && synapseCounts != 0) {
	// get the index of where this neuron's list of synapses are
	BGSIZE beginIndex = edgeIndexMapDevice->incomingEdgeBegin_[idx];
	// get the memory location of where that list begins
	BGSIZE *incomingMapBegin = &(edgeIndexMapDevice->incomingEdgeIndexMap_[beginIndex]);
	// for each synapse, let them know we have fired
	switch (classSynapses_d) {
	case classAllSTDPSynapses:
	case classAllDynamicSTDPSynapses:
	for (BGSIZE i = 0; i < synapseCounts; i++) {
	postSTDPSynapseSpikeHitDevice(
	incomingMapBegin[i],
	static_cast<AllSTDPSynapsesDeviceProperties *>(allEdgesDevice));
	} // end for
	break;
	case classAllSpikingSynapses:
	case classAllDSSynapses:
	for (BGSIZE i = 0; i < synapseCounts; i++) {
	postSpikingSynapsesSpikeHitDevice(incomingMapBegin[i], allEdgesDevice);
	} // end for
	break;
	default:
	assert(false);
	} // end switch
	}
	} else {