v2.0.0

• This release introduces major changes to how Geneagrapher works internally. Previously, the logic to retrieve information from the Mathematics Genealogy Project and build graphs was in Geneagrapher. As of this release, that work is done by a service that Geneagrapher makes requests to. That service is built using geneagrapher-core.
• Graph building is now more flexible. Previously, traversal from the graph's starting nodes was either all in the advisor direction or in the descendant direction. Traversal directions are now specified on a per-node basis. This has led to some syntax changes in the tool's usage, so commands that worked in Geneagrapher 1.0.0 will not work in 2.0.0.
• This is the first version of Geneagrapher targeted only for Python 3.
• The test system was completely overhauled and modernized.
• The source code now uses type hints.
• A CI workflow has been added to automatically run code formatting, linter, and type hint checks, as well as the test suite.