E-graphs Simple

Intended as example / learning software.

for a thesis project.

reading guide:

-lib.rs collects all the files and contains all the tests.

-main.rs is just to test importing lib.rs.

-id.rs, eclass.rs and enode.rs only contain their respective enums and structs.

-util.rs contains some miscelanious functions.

-pattern.rs contains pattern enums and rule structs and methods to create them.

-egraphs contains the egraph struct and all its functions, all the magic happens here.