Enabled source prefiltering on all calculators
Merge branch 'master' of github.com:gem/oq-engine into prefiltering
Prefiltering is enabled only if there are less than 10,000 sites
Restored prefiltering in the worker
Restored source filtering during disaggregation
Added a test for the prefiltering functionality
Fixed an indentation error
Fixed two docstrings
Merge pull request #1340 from gem/prefiltering

Prefiltering sources in all calculators