Docker

See merge request !2

We can't remove it otherwise we have object of type closure is not subsettable when running in parallel.

Models needs to be initialized since now we use models_list. Remove more variables and call garbage collector.

Order the variables, only save into memory current status if the user wants to save the runs. Call garbage collector after each run.

Avoid re-assignments to the same variable name so we can delete the content and help the garbage collector to clean memory.

When the user does not need to save the runs, then we should not build a complete Habitat Class object which takes a lot of space in memory.

Remove assignment which do not make sense. Drop some more structures before returning to release memory.

The user can now specify the max number of cores. This helps us to control the ratio of available cores and main memory.