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* Python research import improvements
- Improve start.py for research env
- Remove unrequired imports
* Centralize algorithm imports
* Add regression test GH action
* Unit test python import clean up
* Join research and main imports
* More python import clean up
* Fix failing skipped regression algorithm
`BaseDictionary` is an abstract implementation of `IExtendedDictionary` keyed by `Symbol` that implements Python `dict` methods. `Slice`, `DataDictionary`, `SecurityManager`, and `SecurityPortfolioManager` derives from it in order to behave like Python `dict`.