Clean up SLOWMO terms

[faridseifi]

Clean up unused terms and move terms to PSDO and CPO, use Dublin core, schema.org or others instead of creating new terms, add terms that are missing.

Rename SLOWMO to SCAFFOLD. Consider adding these to scaffold context file.

Candidate seems to be central to SCAFFOLD. May be most of SCAFFOLD terms are really about candidates. Maybe we need a candidate ontology.