finished implementing most models, except for oqmif, riski, riskr
finished implementing most models, except for oqmif, riski, riskr

I still need to double-check everything, add documentation, and add validation constraints


Former-commit-id: 231d1e1c66124eb978a10a586871e3a1a456c911 [formerly f3ef662cb07848ed96dc24073f604e6f8e5efb00]
Former-commit-id: c2353c00ac3f432ea5c9aa5108a7205f1e0bebf5
gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine