NF: Process TRACULA data into a node table.
NF: Process TRACULA data into a node table.

Addresses #174

Partially addresses #163

Still remaining: streamline representation.

richford/AFQ-Browser,arokem/AFQ-Browser,yeatmanlab/AFQ-Browser,richford/AFQ-viz,richford/AFQ-viz,yeatmanlab/AFQ-viz,arokem/AFQ-Browser,yeatmanlab/AFQ-Browser,arokem/AFQ-Browser,richford/AFQ-Browser,yeatmanlab/AFQ-Browser,richford/AFQ-Browser,yeatmanlab/AFQ-viz