Numerapi

- return filepath from `download_dataset`

- add `modelid_to_modelname` method
- fix `stake_set`
- add option to adjust connection timeout when upload predictionions (PR 97)
- remove deprecated `download_latest_data`
- add `set_global_data_dir` method
- docs

- add `data_datestamp` argument to `upload_predictions` - this will allow
submitting predictions using data from a previous round.

- fix `SignalsAPI.daily_model_performances`
- adding all the new metrics (RIC, CorrV4, FncV4, etc) to `diagnostics`

- `stake_get` - updated to migrate away from deprecated API endpoint
- remove deprecated `SignalsAPI.daily_user_performances`
- remove deprecated `SignalsAPI.daily_submissions_performances`
- remove `round_details` - no longer supported by Numerai
- remove deprecated `daily_submissions_performances`

- numerapi-cli: make `check-new-round` more robust
- more robust `check_new_round` and `check_round_open` - working around some
edge cases, that occur during the time without any active round.