Methods and test vectors

Each method a published figure names in its method field, with its version, formula, rules and test vectors: inputs with the output the method gives, to check an implementation against. It holds ti-ownership/1, the ETF ownership ledger, ti-ownership-index/1 and ti-overlap/1. A change to what a method computes from inputs it already accepted is a new version, never an edit of the one published. A rule for an input it did not accept before is added to the version with its own test vector, and changes gives the day it was first published.