Fix #80 -- improve efficiency of delete_vertex and #85 improve efficiency of replace_vertex

[stevensonmt]

• fix Poor performance of Graph.delete_vertex/2 in large graphs #80
• ready for PR

[stevensonmt]

I don't understand the errors from the CI run. If someone can point me in the right direction I will try to resolve it, but I think it might be pointing more to how the CI runs are configured?

[stevensonmt]

included #85 in this PR.

[stevensonmt]

Please double check that I've not mixed up incident and emanating edges here.

[stevensonmt]

sorry, don't know why that stupid lexical log keeps showing up even after adding it to gitignore and deleting the directory (vim creates it again when it tries to use lexical for LSP).

[bartblast]

Hey @bitwalker!

Just checking in about this PR - the performance fixes here would be really helpful for Hologram when handling large graphs. Any chance you'll be able to take a look at it soon?

[zblanco]

I ran into this CI issue with my PR a while back and had to some different minor versions as old ones had their repos taken down. stevensonmt#1 adjusts the github workflow to explicitly reference some OTP / elixir versions that I could find pullable repos for.