Hera-sim

===================
This release heavily focuses on performance of the visibility simulators, and in
particular the ``VisCPU`` simulator.

Fixed
-----
- Passing ``spline_interp_opts`` now correctly pipes these options through to the
visibility simulators.

Added
-----
- New ``_blt_order_kws`` class-attribute for ``VisibilitySimulator`` subclasses, that
can be used to create the mock metadata in an order corresponding to that required
by the simulator (instead of re-ordering after data creation, which can take some
time).
- New optional ``compress_data_model()`` method on ``VisibilitySimulator`` subclasses
that allows unnecessary metadata in the ``UVData`` object to be dropped before
simulation (can be restored afterwards with the associated ``restore_data_model()``).
This can reduce peak memory usage.
- New ``check_antenna_conjugation`` parameter for the ``VisCPU`` simulator, to allow
turning off checks for antenna conjugation, which takes time and is unnecessary for
mock datasets.
- Dependency on ``hera-cli-utils`` which adds options like ``--log-level`` and ``--profile``
to ``hera-sim-vis.py``.
- Option to use a taper in generating a bandpass.
- ``utils.tanh_window`` function for generating a two-sided tanh window.
- ``interpolators.Reflection`` class for building a complex reflection
coefficient interpolator from a ``npz`` archive.
- Reflection coefficient and beam integral ``npz`` archives for the phase 1
and phase 4 systems (i.e., dipole feed and Vivaldi feed).

Changed
-------
- ``run_check_acceptability`` is now ``False`` by default when constructing simulations
from obsparams configuration files, to improve performance.
- For ``VisCPU`` simulator, we no longer copy the whole data array when simulating, but
instead just fill the existing one, to save on peak RAM.
- Made ``VisCPU._reorder_vis()`` much faster (like 99% time reduction).
- The ``--compress`` option to ``hera-sim-vis.py`` is no longer a boolean flag but
takes a file argument. This file will be written as a cache of the baseline-time indices
required to keep when compressing by redundancy.

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

Breaking Changes
----------------
- Removed the ``HealVis`` wrapper. Use ``pyuvsim`` instead.

Changed
-------
- Updated package to always use future array shapes for ``pyuvdata`` objects (this
includes updates to ``PolyBeam`` and ``Simulator`` objects amongst others).

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

Changed
-------
- Coupling matrix calculation in :class:`~.sigchain.MutualCoupling` has been updated
to correctly calculate the coupling coefficients from the provided E-field beam.

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

Added
-----
- :class:`~.sigchain.MutualCoupling` class that simulates the systematic described in Josaitis
et al. 2021.
- New class attributes for the :class:`~.SimulationComponent` class:
- ``return_type`` specifies what type of return value to expect;
- ``attrs_to_pull`` specifies which ``Simulator`` attributes to use.
- Some helper functions for :class:`~.sigchain.MutualCoupling` matrix multiplications.
- More attributes from the underlying ``UVData`` object exposed to the :class:`~.Simulator`.

Changed
-------
- ``Simulator._update_args`` logic has been improved.
- :class:`~.Simulator` attributes ``lsts``, ``times``, and ``freqs`` are no longer cached.

======

Removed
-------

- Finally removed ability to set ``use_pixel_beams`` and ``bm_pix`` on the VisCPU
simulator. This was removed in v1.0.0 of ``vis_cpu``.
- Official support for py37.

Internals
---------

- Added isort and pyupgrade pre-commit hooks for cleaner code.

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

Added
-----
- ``NotImplementedError`` raised when trying to simulate noise using an interpolated
sky temperature and phase-wrapped LSTs.
- More comparison tests of pyuvsim wrapper.

Fixed
-----
- Inferred integration time in ``ThermalNoise`` when phase-wrapped LSTs are used.
- Added ``**kwargs`` to ``PolyBeam.interp`` method to match UVBeam.
- healvis wrapper properly sets cross-pol visibilities to zero.

Changed
-------
- Temporarily forced all UVData objects in the code to use current array shapes.