Adding OEP and AEP for event-based risk and damage calculations about oq-engine

[CatalinaYepes]

LGTM to produce by default the 3 types of curves. However, I don’t like the way the new parameter was introduced, it does not follow the OQ job.ini standards.

aggregate_loss_curves_type = ,_oep ,_aep

• The comma is part of the parameter instead of the field separator (super confusing). Right now the separator is the space.

• If the user wants only EP curves, then the parameter should be set to aggregate_loss_curves_type = . It is ambiguous, but it works with the current implementation.

• The user can not get only OEP or AEP curves. if the parameter is set to `aggregate_loss_curves_type = ,_aep , the output includes EP and AEP. Any reason why we need to produce EP by default?

My recommendation is to implement the job.ini parameter as initially suggested
aggregate_loss_curves_type = ep, oep, aep
Where the comma is used to separate the fields. Internally, OQ can have a dictionary to name the functions as required:
{'ep':'', 'oep':'_oep', 'aep':'_aep'}

[ptormene]

As requested by @CatalinaYepes, I am listing here the deviations and missing details in the current implementation, with respect to the above specifications:

• the new ini parameter is called aggregate_loss_curves_types and its value is ,_oep,_aep by default, meaning that loss, loss_aep and loss_oep will be computed, unless otherwise specified. It is a fast operation, so it's worth computing everything by default. The reason of the seemingly strange format of the parameter is because it is convenient for the sake of the implementation of this feature;
• in order to keep consistency with the past, the field that was called loss before will not be renamed into loss_ep;
• consequences other than loss are still unchanged
• also reinsurance-related functionalities are not implemented yet

[ptormene]

The points discussed above have been addressed, so now the format for the aggregate_loss_curves_types parameter is as suggested, the EP curves are optional and also reinsurance curves are computed.
Please @CatalinaYepes, can you check if everything is in place or if you see anything missing?