Moved common code to abstract base class.
Moved access to the initial state as well
Merge branch 'feature/refactor_ctmc_system' into develop
Merged classes
Moved concrete state spaces to separate module
Merge branch 'feature/merge_minimal_state_space_classes' into develop
Moved general code to transitions.py
Refactored migration model
refactored psmc
Moved projection code to a function
Merge branch 'feature/refactor_matrix_computations' into develop
Documentation string for the forwarders.
Removed unused import
Removed test code for classes that have been moved
A little code clean-up
Merge branch 'develop' into feature/psmc_simulations