K-Shortest Path- Yen's algorithm

Based on Yen’s algorithm, returns the K shortest paths between a source and a destination.

This function is based on Yen's k-Shortest Path algorithm:
J. Y. Yen, "Finding the K shortest loopless paths in a network", Management Science 17:712–716, 1971.

It returns:
1) [shortestPaths]: the list of K shortest paths (in cell array 1xK)
2) [totalCosts] : costs of the K shortest paths (in array 1xK)
Yen's algorithm prevents loops.

This function calls a slightly modified/simplified function dijkstra() (submitted by Xiaodong Wang, 2004)

The Network/Graph of N nodes is fed in the form of a NXN netCostMatrix which must have positive weights/costs.

IMPORTANT: see 'TestKShortestPath.m' and 'Test graph (case 1).pdf' for netCostMatrix format.