This is related to the following tickets:
#2723 and #2897

In fmi.pyx:
 -- method get_directional_derivative in FMUModelBase2 is moved to FMUModelME2
 -- methods get_input_list and get_output_list are created in FMUModelBase2

In fmi_algorithm_drivers.py:
 -- In the class AssimuloFMIAlg a new if-statement is used to handle both
     ME1 and ME2 models

In assimulo_interface.py:
 -- New classes FMIODE2 and FMIODESENS2 are created for ME2-models in the same manner as FMIODE and FMIODESENS exists for ME1-models. The new FMIODE2 class can handle Jacobians provided by the FMU.
Renamed BaseModel to ModelBase. Related to ticket:2580