Adding single swapping functionality for network

[i-am-Nathan]

After initial K facility has been selected:

• [x] While looping through all the facilities, select the next fac node in the facnodelist to swap to

• [x] if swapping reduces the total cost then swap

Lowest score = most optimal

[JunoJin]

pseudocode: Get K facs find distances from each 'selected' facnode using Dijkstra and on each resnode, store the node and its distance to it run through resnodes and get the facnode with the shortest path to to compute distance for score next iteration by checking the next facnode, do the same and if score is better than previous then swap and overwrite after iterating just return the final score

[JunoJin]

done via commit 7956c9ba0ef0248208525fdc82b27668f3127dcd