Update Event Based algorithm

[matley]

The new algorithm should compute loss curves in a different way. Here on, a sample code in Matlab:

maxValue = max(aggLosses)
Losses=linspace(0,maxValue,100);
excLosses=Losses;
for i=1:length(excLosses)
   excLosses(i)=sum(aggLosses>Losses(i));
end
rates=excLosses/TSES;
ProbExc=1-exp(-rates.*50);

where aggLosses is the result of applying the vulnerability function to a set of ground motion values, 100 is the loss curve resolution. The curves is composed by Losses over ProbExc

[Michele Simionato (michele-simionato)]

Implement in https://github.com/gem/oq-risklib/pull/52