Fix equality for array coordinates

Closes #1832
Added test for #1832 failure mode
Add test for #2037 failure mode
update changelog
Get `Longitude` sign to come out right from `wrap_angle` when 0

Closes #2037
Fix test that incorrectly had '-0h00m00s 0d00m00s' and similar
add missing __all__ to convolution/core.py
Correct API module names

Make it so that the stub pages generated with automodapi have the paths
to the function or class that a user should use. For example, the Table
class now appears as astropy.table.Table rather than
astropy.table.table.Table.
Explicitly point to kernel stub pages

This is necessary under the revised automodsumm to correctly link
to already-created stub pages. It should be possible to use automodsumm with
the `:classes-only:` option, but that doesn't seem to be working.
Add patched version of viewcode sphinx extension

Using local names in autosummary fails to link to raw code with the
current released version of the viewcode sphinx extension (Sphinx v1.1.3).
This patched version fixes the problem. It can be removed once the problem
is fixed in Sphinx proper (there is an issue open).
Adjust automodsumm to truly act like `currentmodule` is in force
Added examples for formats in time documentation
Added examples to docstrings for TimeFormat subclasses
Made documentation consistent with numpydoc convention
Fit equals signs to full width of table column
Fix CONSTRAINTS_DOC formatting in modeling docs
Fix x, y order with numpy.mgrid usage
vos_catalog.py: fix use of format() for compat with python 2.6
another {} format() problem in test_cosmology
Fix some links in sphinx-generated html docs