Add reduce operation to stylesheet

Add option for client to perform transitive reduction

Different modes:

- ignore edge labels
- perform TR on a per-label basis
- inference based TR (will require some level of reasoning on client)

The issue names no files, tests, or entry points. Start by locating the stylesheet option handling and client-side graph reduction code, then determine how the three listed modes should be represented; done means the client can perform transitive reduction while supporting ignored labels, per-label reduction, and inference-based reduction.

Written by the indexing model from the issue text.