Spectral-cube

------------------
- Add SpectralCube.with_beam and Projection.with_beam for attaching
beam objects. Raise error for position-spectral slices of VRSCs
(https://github.com/radio-astro-tools/spectral-cube/pull/433)
- Raise a nicer error if no data is present in the default or
selected HDU
(https://github.com/radio-astro-tools/spectral-cube/pull/424)
- Check mask inputs to OneDSpectrum and add mask handling for
OneDSpectrum.spectral_interpolate
(https://github.com/radio-astro-tools/spectral-cube/pull/400)
- Improve exception if cube does not have two celestial and one
spectral dimesnion
(https://github.com/radio-astro-tools/spectral-cube/pull/425)
- Add creating a Projection from a FITS HDU
(https://github.com/radio-astro-tools/spectral-cube/pull/376)
- Deprecate numpy <=1.8 because nanmedian is needed
(https://github.com/radio-astro-tools/spectral-cube/pull/373)
- Add tools for masking bad beams in VaryingResolutionSpectralCubes
(https://github.com/radio-astro-tools/spectral-cube/pull/373)
- Don't warn if no beam was found in a cube
(https://github.com/radio-astro-tools/spectral-cube/pull/422)

------------------
- Handle equal beams when convolving cubes spatially.
(https://github.com/radio-astro-tools/spectral-cube/pull/356)
- Whole cube convolution & reprojection has been added, including tools to
smooth spectrally and spatially to force two cubes onto an identical grid.
(https://github.com/radio-astro-tools/spectral-cube/pull/313)
- Bugfix: files larger than the available memory are now readable again
because ``spectral-cube`` does not encourage you to modify cubes inplace
(https://github.com/radio-astro-tools/spectral-cube/pull/299)
- Cube planes with bad beams will be masked out
(https://github.com/radio-astro-tools/spectral-cube/pull/298)
- Added a new cube type, VaryingResolutionSpectralCube, meant to handle
CASA-produced cubes that have different beams in each channel
(https://github.com/radio-astro-tools/spectral-cube/pull/292)
- Added tests for new functionality in OneDSpectrum
(https://github.com/radio-astro-tools/spectral-cube/pull/277)
- Split out common functionality between SpectralCube and LowerDimensionalObject
into BaseNDClass and SpectralAxisMixinClass
(https://github.com/radio-astro-tools/spectral-cube/pull/274)
- added new linewidth_sigma and linewidth_fwhm methods to SpectralCube for
computing linewidth maps, and make sure the documentation is clear that
moment(order=2) is a variance map.
(https://github.com/radio-astro-tools/spectral-cube/pull/275)
- fixed significant error when the cube WCS includes a cd matrix. This
error resulted in incorrect spectral coordinate conversions
(https://github.com/radio-astro-tools/spectral-cube/pull/276)

------------------

- Bugfix in configuration

------------------

- Preserve metadata when making projections
(https://github.com/radio-astro-tools/spectral-cube/pull/250)
- bugfix: cube._data cannot be a quantity
(https://github.com/radio-astro-tools/spectral-cube/pull/251)
- partial fix for ds9 import bug
(https://github.com/radio-astro-tools/spectral-cube/pull/253)
- preserve WCS information in projections
(https://github.com/radio-astro-tools/spectral-cube/pull/256)
- whitespace stripped from BUNIT
(https://github.com/radio-astro-tools/spectral-cube/pull/257)
- bugfix: sometimes cube would be read into memory when it should not be
(https://github.com/radio-astro-tools/spectral-cube/pull/259)
- more projection preservation fixes
(https://github.com/radio-astro-tools/spectral-cube/pull/265)
- correct jy/beam capitalization
(https://github.com/radio-astro-tools/spectral-cube/pull/267)
- convenience attribute for beam access
(https://github.com/radio-astro-tools/spectral-cube/pull/268)
- fix beam reading, which would claim failure even during success
(https://github.com/radio-astro-tools/spectral-cube/pull/271)

------------------

- Add experimental line-finding tool using astroquery.splatalogue
(https://github.com/radio-astro-tools/spectral-cube/pull/210)
- Bugfixes (211,212,217)
- Add arithmetic operations (add, subtract, divide, multiply, power)
(https://github.com/radio-astro-tools/spectral-cube/pull/220).
These operations will not be permitted on large cubes by default, but will
require the user to specify that they are allowed using the attribute
``allow_huge_operations``
- Implemented slicewise stddev and mean
(https://github.com/radio-astro-tools/spectral-cube/pull/225)
- Bugfix: prevent a memory leak when creating a large number of Cubes
(https://github.com/radio-astro-tools/spectral-cube/pull/233)
- Provide a ``base`` attribute so that tools like joblib can operate on
``SpectralCube`` s as memory maps
(https://github.com/radio-astro-tools/spectral-cube/pull/230)
- Masks have a quicklook method
(https://github.com/radio-astro-tools/spectral-cube/pull/228)
- Memory mapping can be disabled
(https://github.com/radio-astro-tools/spectral-cube/pull/226)
- Add xor operations for Masks
(https://github.com/radio-astro-tools/spectral-cube/pull/241)
- Added a new StokesSpectralCube class to deal with 4-d cubes
(https://github.com/radio-astro-tools/spectral-cube/pull/249)

------------------

- Output mask as a CASA image https://github.com/radio-astro-tools/spectral-cube/pull/171
- ytcube exports to .obj and .ply too
https://github.com/radio-astro-tools/spectral-cube/pull/173
- Fix air wavelengths, which were mistreated
(https://github.com/radio-astro-tools/spectral-cube/pull/186)
- Add support for sum/mean/std over both spatial axes to return a
OneDSpectrum object. This PR also removes numpy 1.5-1.7 tests, since
many `spectral_cube` functions are not compatible with these versions
of numpy (https://github.com/radio-astro-tools/spectral-cube/pull/188)