oq-engine: disaggregation by ruptures

[matley]

Event Based Risk Calculator allows calculating contributions to the losses in a specific point (given a probability of exceedance) in terms of ruptures.

More precisely, ruptures need to be grouped by distance/magnitude and by coordinates. Then, for each group a loss fraction in specific points needs to be computed.

To this aim, a nrml format and an output type have been defined called loss-fractions.

New (optional) configuration parameters will be added to job.ini:

sites_disagg = list of points where disaggregation will be done
coordinate_bin_width = bin width used to group ruptures together
distance_bin_width = bin width used to group ruptures with magnitude
mag_bin_width = bin width used to group ruptures with distance

[matley (matley)]

https://github.com/gem/oq-engine/pull/1114