Support Python classes as an option to define cell templates

[salvadord]

Some of the NEURON developers were surprised that Python classes were not supported as an option to define cell templates -- the preferred option for cell templates is now Python classes instead of hoc templates. See eg. tutorial https://neuron.yale.edu/neuron/static/docs/neuronpython/ballandstick2.html . Also, many models on ModelDB use Python classes for cell templates: https://senselab.med.yale.edu/ModelDB/ShowModel.cshtml?model=229585&file=/purkinjecell/Purkinje.py#tabs-2 , https://senselab.med.yale.edu/ModelDB/ShowModel.cshtml?model=195615&file=/spidemo/SPI6.py#tabs-2 , https://senselab.med.yale.edu/ModelDB/ShowModel.cshtml?model=237653&file=/Beskow/MSN_builder.py#tabs-2 , https://senselab.med.yale.edu/ModelDB/ShowModel.cshtml?model=225075&file=/HirataniFukai2018/libcell.py#tabs-2

[hernando]

Is the solution as simple as adding an additional item to the specification of valid model_templates?
For example:

• py: The template is Python file containing a NEURON Python class. Valid for both biophysical and single_compartment model types.

The question is: How dynamics_params can specify parameter overrides from the template in this case?