Added help to the tool, use "oqrev --help" to get it.
Added help to the tool, use "oqrev --help" to get it.


Former-commit-id: 2aa8952e1ade7ed6a0f8b044dec5238fca28c5f5 [formerly 1df37a21a72a47c97da58bbfdb2499d49ff6d5f1]
Former-commit-id: 5e97966b12c3568589f42be1c37efb5701f86445
gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine