Split the initialization of dose_world from entities class in SIM_01.py about dose HOT 1 CLOSED

To 'split' world initialization from entities (now simulation_functions) is of no use as some functions inside simulation_functions require the initialization of world inside the same class (such as ecoregulate(self)).

Instead of removing the creation of the world inside the simulation_functions and possibly making things more complicated, the option to 'hide' the initialization of the world inside dose.py's dose_functions (previously simulation_functions) seems to be a better alternative.

With this implemented, the user is now incapable of messing up the creation of the world by removing the option to do so inside SIM_01.py. (See commit: 956f479)

from dose.