Pyportfolio

- Handle casparser exceptions like wrong password (we print error and gracefully abort)
- Minor internal changes to how __version__ is computed

First alpha release of pyportfolio.

- Scheme and Transaction pydantic models
- Portfolio export to dict
- LTCG Tax Harvesting
- Portfolio Summary and Break Up

BREAKING CHANGES
We no longer have a Scheme class. All methods take the Scheme model as param, which is interoperable.