Added extract_source script
Added extract_source script


Former-commit-id: 07bd4b78ef1d2cd6b3947aef6e49e6fedb677c61 [formerly 5c7a0056330bb12f601dcb19bc74d77d64b37ec9]
Former-commit-id: 037c80321929d90a5a6194311602e67253a79acc
gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine