JSON-LD Star, YAML-LD Star

[westurner]

• https://json-ld.github.io/json-ld-star/#basic-concepts
• YAML-LD #110
• decide on the short names of the specifications w3c/rdf-star-wg#4

[aucampia]

@westurner please note that this repo is no longer maintained, JSON-LD support is now part of RDFLib core. We also plan on incorporating pyld for better JSON-LD support sometime.