Politsiyakat

- Refines multithreading and adds asynchronous IO
- Replaces previous flaggers:
- Track auto-correlations per scan for a set of fields. Flags outliers based on group and antenna sigmas
- Track calibrator phase per scan. Flags outliers based on group and baseline sigmas. Applies flags to target scans between calibrator scans.
- Adds waterfall plots for phase and spectrum

This release adds several bug fixes and new features:

- Multi-SPW data are now correctly phase flagged with the original excessive phase error flagger
- Users can now specify fields and calibrator fields to flag. This can be useful to combine information from multiple calibrators when computing statistical information about phase and amplitude problems affecting baselines.
- Adds a task to separate scans per field and flag targets based on excessive phase and amplitude drifts.
- Experimental task to flag antennas with most of their baselines fully flagged. This task is subject to further development.
- Add Pypi support

Basic phase flagging based on calibrator