Hera-sim

===================

Added
-----
- New ``OverAirCrossCoupling`` class to better model crosstalk in H1C data.

Changed
-------
- Slightly modified ``Simulator`` logic for automatically choosing parameter values.
This extends the number of cases the class can handle, but will be changed in a
future update.

===================

Added
-----
- New VisibilitySimulator interface. See the `<https://hera-sim.readthedocs.io/en/latest/tutorials/visibility_simulator.html> Visibility Simulator Tutorial`_
for details. This is a breaking change for usage of the visibility simulators, and
includes more robust handling of polarization, fixed ordering of data when put back
into the ``UVData`` objects, more native support for using ``pyradiosky`` to define
the sky model, and improved support for ``vis_cpu``.
- Interface directly to the ``pyuvsim`` simulation engine.
- Ability to load tutorial data from the installed package.
- New and refactored tests for visibility simulations.

Fixed
-----
- default ``feed_array`` for ``PolyBeam`` fixed.

Changed
-------
- Updated tutorial for the visibility simulator interface (see above link).
- ``vis_cpu`` made an optional extra
- removed the ``conversions`` module, which is now in the ``vis_cpu`` package.
- Can now properly use ``pyuvdata>=2.2.0``.

===================

Added
-----
- Add a Zernike polynomial beam model.

===================

Added
-----
- Enable polarization support for ``vis_cpu`` (handles polarized primary beams, but
only Stokes I sky model so far)
- Add a polarized version of the analytic PolyBeam model.

===================

Fixed
-----
- Bug in retrieval of unique LSTs by :class:`~.Simulator` when a blt-order other than
time-baseline is used has been fixed. LSTs should now be correctly retrieved.
- :func:`~.io.empty_uvdata` now sets the ``phase_type`` attribute to "drift".

===================

Added
-----

Fixed
-----
- Discrepancy in :class:`~.foregrounds.PointSourceForeground` documentation and actual
implementation has been resolved. Simulated foregrounds now look reasonable.

Changed
-------
- The time parameters used for generating an example ``Simulator`` instance in the tutorial
have been updated to match their description.
- :class:`~.Simulator` tutorial has been changed slightly to account for the foreground fix.