PySD data files load does not allow for encoding

[rachieg2]

Even though the Columns() object has an option for encoding, this parameter does not appear to be passed through the helpers to load_vensim() or any similar top-level function. Please allow me to specify encoding when I pass data files to the load. Thanks!

[enekomartinmartinez]

Sure, I could add that support. Would you have a common encoding for all the files? I would prefer to have a str argument but I could make it a dict if necessary.

[enekomartinmartinez]

Let me know if the changes in https://github.com/SDXorg/pysd/tree/add_tabdata_encoding fill your requirements and if not if you need access to other arguments. If so, I could try to add a more generic kwarg dict for these files.