Aipy

- Remove Astropy version cap; it was intended to promote simultaneous Python
2/3 compatibility, but if someone wants to use the newer version, that's
fine too.
- Fix a bug in the Healpix wrapper
([52](https://github.com/HERA-Team/aipy/pull/52)).
- Fix some lingering Python 2/3 compatibility issues
([51](https://github.com/HERA-Team/aipy/pull/51)).
- Honor `pos_def` in the 1D real CLEAN
([44](https://github.com/HERA-Team/aipy/issues/44))
- Install the Helmboldt catalog data files, which were mistakenly not being
included in installations
([45](https://github.com/HERA-Team/aipy/issues/45))
- Rename the package directory in the source tree from `aipy_src` to `aipy`.

- Fix generation of the package description in `setup.py`
([46](https://github.com/HERA-Team/aipy/issues/46),
[47](https://github.com/HERA-Team/aipy/issues/47))
- Fix division that should have become integer division
([48](https://github.com/HERA-Team/aipy/issues/48))

- Make compatible with Python 3; remove scipy and healpix borrows.

2.x series

- No changelog was maintained. Consult the Git history.

* Added some performance enhancements
* Miriad.UV files can now store data as both shorts and as float32 (avoiding dynamic range problems)
* Various bugfixes
* Because of stability of 0.X.X series, we've promoted this to a non-beta release!

* Made some major naming changes in preparation for an AIPY publication. These include
renaming aipy.ant to aipy.phs, aipy.sim to aipy.amp, aipy.loc to aipy.cal.
* Renamed BeamFlat to just plain Beam
* Changed the -l options (for "loc files") in scripting interfaces to -C (for "cal" files)
* Added support in scripting interface channel selection for constructions of the form
0_10_2, meaning channels 0 to 10 (including endpoints), counting by 2.
* Refactored code so source spectra are computed internally to RadioBodys, and are
accessed through the get_jys() method. Added an update_jys() method for computing
a source spectrum for specified frequencies without needing an AntennaArray object.
* Added a get_afreqs() method to AntennaArrays to elucidate the opaque incantation;
"AntennaArray.ants[0].beam.afreqs."
* Added a system support for adding source catalogs through src.py calling catalog
interfaces stored in the _srcs directory. Made the Helmboldt catalog the default
catalog that AIPY comes with (since it's pretty small and geared toward low frequencies).
* Added unit tests (in "test" directory) for the most-used modules, and will continue to
add them as other modules are revisited. There is also a script called
"script_battery.sh" that does basic exercising of most AIPY scripts.
* In Antennas, grouped delay/offset into an array called phsoff which is a phase
polynomial in frequency.
* Couple of bugfixes on how objects are updated (now made explicit with "update()"
methods) and fixed an array shape bug in Antenna.refract()
* Fixed a bug in filter_src.py where data were zeroed when a source is below the horizon.
* Transitioned all nomenclature from "Fringe-Rate" to "Delay-Rate" as per
Parsons & Backer (2009) in AJ.
* Changed how fit parameters are input in scripting module
* Bugfix for when resolution effects are taken into account in
AntennaArray.gen_phs.
* Bugfix in xrfi.py for flagging by integration
* Improved filtering in filter_src.py to use padding and optionally passband
information.
* Added script srclist.py
* Added masking by wieght to plot_map.py

* Fixed a data-type error for Healpix maps that aren't doubles
* Added max/drng/cmap parameters to standard command-line options
* Started adding unit tests
* Changed noise option in mdlvis.py to add noise in Jy (not data) units.
* Changed behavior of reducing NSIDE in Healpix maps to sum instead of average.
* Bugfix on extracting source below the horizon in filter_src.py
* Work aound problem with numpy MA arrays not having a mask if entire image
is valid.
* Added new option (0,1,2)_3 for specifying antennas on the command line.