v0.7.8 - Add TSV writer to support SemanticSQL

What's Changed

• Update docs, tox, and package metadata by @cthoyt in #105
• Add TSV writer and update other writers' docs by @cthoyt in #107 (motivated by @joeflack4)

Full Changelog: v0.7.7...v0.7.8

Example:

import curies
converter = curies.load_prefix_map({
    "CHEBI": "http://purl.obolibrary.org/obo/CHEBI_",
})
curies.write_tsv(converter, "example_context.tsv")