feat: add new summary statistics

[ntalluri]

Adding in new statistics mentioned in #349.

[tristan-f-r]

(Thanks for using the semantic commit style in the PR header! I use that commit style because it makes the changelog easier to skim [see the 0.5 release changelog for an example])

[agitter]

I haven't carefully reviewed the expected output files yet.

[read-the-docs-community]

Documentation build overview

📚 spras | 🛠️ Build #29239897 | 📁 Comparing e181563 against latest (647f4a1)

🔍 Preview build

Show files changed (2 files in total): 📝 2 modified | ➕ 0 added | ➖ 0 deleted

File	Status
fordevs/spras.html	📝 modified
prms/oi1.html	📝 modified

Fixed issues

[agitter]

I have one final small question, and then this is essentially ready to merge.

The discussion of how these summary statistics assume an undirected graph and convert directed edges does point out that we need to start writing docs. That can happen separately.