added db_list_generations() function to list the available generations within a simulation in the database log, and db_list_datafields() to list the available types of data within a simulation in the database log
added db_get_ecosystem()
added db_list_population_name, db_get_organisms_status, db_get_organisms_genome, and db_get_organisms_sequences functions
cleaning up imports (only those needed by users are imported)
cleaning up imports (only those needed by users are imported)
Merge branch 'master' of https://github.com/mauriceling/dose
Reconstructed simulate() and revive_simulation() in dose.py
Updated write_parameters() in simulation_calls.py
Reconstructed 00_test_simulation.py in preparation of 08_revive_simulation_03