#42 JSIM: allow closed class jobs to be 'sinked'

[Bertoli Marco]

In closed models with a fork acting as a split (without a join) it is necessary to allow closed jobs to be 'sinked' otherwise number of jobs will increase to infinity. There are special checks to avoid closed class jobs to be put in sinks that have to be removed.

Please note also that in a closed model, if every job is dropped, the simulation must terminate.

[Giuliano Casale]

This appears handled in a different way in 0.9.4. A warning notifies that JMT automatically set the routing of closed classes to drop as 0. This seems much more recent that the above issue, hence we will keep this default behaviour.