Rfcx

New features
- Added `RFCX_API_URL` environment variable to support alternative API environments

Modified functionality:
- Avoid using media API and switch to downloading single or ranges of segments/recordings
- Renamed `download_audio_files` to `download_segments` (breaking change)
- Renamed `download_audio_file` to `download_segment` (breaking change)
- Can use datetime or string (in ISO9 format) as arguments on any timestamp fields
- Renamed confusing `only_public` argument to `include_public` on get `streams`

Modified functionality:
- `streams()`: Add ability to custom retrieve fields
- `projects()`: Add ability to custom retrieve fields

Bug fix:
- Fix `streams()` to not use only_public and only_delete as default

Documentation: https://rfcx.github.io/rfcx-sdk-python/

New functionality:
- stream(): Get stream information

Bug fixes:
- Fix `only_public` and `only_delete` to call boolean fields on API correctly

New functionality:
- `projects()`: Get project list

Modified functionality:
- Rename `authentication()` to `authenticate()`
- Rename `download_file()` to `download_audio_file()`
- Rename `download_file_segments()` to `download_audio_files()`
- `streams()`: Add ability to get stream by name query

Bug fixes:
- Update stream segment to use new API endpoint
- Fix `download_audio_files()` not download audio properly

Modified functionality:
- `authentication()`: Update authentication flow to popup browser and get user token automatically