I've rebased this as a single commit and force-pushed to Raiyan's branch. Raiyan, if you want your original commit history it's at https://github.com/mtorpey/Digraphs/tree/edge-weight-algorithms-raiyan-original

Hopefully we can get this merged at some point!

There's a lot of good stuff in here, but I added a couple of TODOs and there's a little work to be done (probably by me) before it's good to merge. But I'm confident this will broadly make it!

I'm going to try to merge this one bit at a time, to keep things manageable.

Approximate todo list:

• EdgeWeightedDigraphMinimumSpanningTree: Edge-weights #3: minimum spanning trees #650
• DigraphEdgeWeightedShortestPath[s]: Edge weights #4: shortest path(s) #656
• DigraphMaximumFlow/DigraphMinimumCuts
• RandomUniqueEdgeWeightedDigraph
• DigraphFromPath[s]
• DotColoredEdgeWeightedDigraph

The latest version of this that I've got is at https://github.com/mtorpey/Digraphs/tree/edge-weight-algorithms

As mentioned above, I'm making this into PRs one bit at a time.