Use Python class objects rather than raw URIs as arguments

[bbartley]

Some methods require a URI for a PAML class as an argument. For example:

primitive.add_output('measurements', 'http://bioprotocols.org/paml#SampleData')

A more pythonic and user-friendly method signature would be:

primitive.add_output('measurements', SampleData)

The URI corresponding to the Python class can then be looked up in the pySBOL3 parser's registry, which maps URIs to their corresponding Python classes.

[rpgoldman]

Would it make sense to address these entities the way RDFLIB does namespaces ? So PAML.SampleData for example

[jakebeal]

What pySBOL3 does in this case, I believe, is that it will accept either. Can we do that here too?