Bellman Ford - Combinations

[krashish8]

Part of #1648

• Adds Combinations signatures (SQL, C/C++ code, pgTAP tests, docqueries, documentation) to pgr_bellmanFord.
• Adds the missing no-crash pgTAP test and types check for pgr_bellmanFord .
• Updates the release_notes and NEWS file.
• Fixes merge conflict in the shell code.

@pgRouting/admins

[krashish8]

In the code, two such files were present - bellman_ford.c and bellman_ford_neg.c. This may be because the Bellman-Ford algorithm calculates the shortest path where some of the edge weights may be a negative number. I guess having an edge weight with a negative number isn't yet available in pgRouting, therefore the developer might have created another file for positive weights only.

For the combinations signature, I made the necessary changes to both such files.

[cvvergara]

Right now Bellman Ford with negative edges does not exists yet, only positive edges

[cvvergara]

I checked changes, and everything looks fine, Thanks for the missing tests

I will leave here a comment for the future:

• There would be 2 text queries one for positive one for negative edges for the non-combinations signature
  • internally what would need to be decided if the second query is for combinations or for negative edges
    We will deal with the problem when it shows up