input/logictree:
input/logictree:

Refactored some parts to use a slightly more DRY way of referring
to model content, with StringIO objects, etc.


Former-commit-id: 50806a4b2c4d6561d138af4d0b5d94a544ffe216 [formerly 3a454c2f2f56ce61186c72c7ef257a6dfcfa2a2f]
Former-commit-id: e4fe08260383b15f02c93a4d07ecd4a65b4b64d6
gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine