Fix x, y order with numpy.mgrid usage
added note indicating minimum cython version required
This test should use py.test's tmpdir fixture, not tempfile (this test actually breaks on Windows since there are multiple attempts to open the same tempfile)
Merge pull request #2133 from RayPlante/doc-cython-req

added note in install docs indicating minimum cython version required
Fix some links in sphinx-generated html docs
Minor docstring formatting fixes in astropy.stats
Minor docstring formatting fixes in astropy.convolution
Merge pull request #2121 from cdeil/axis_order

Fix x, y order with numpy.mgrid usage
Merge pull request #2109 from cdeil/docstring_html_links

Fix links to other classes in sphinx-generated html docs
Expanded VO catalog and database functionalities. Moved VO exceptions to a separate module. Added tests for new functionalities. Changed inheritance to super.
Updated astropy.vo.validator to use new VO database API. Separated validate and inspect tests. Added new exceptions module under validator.
Fixed codes for Python 3 compatibility and to complete coverage.
Re-organized astropy.vo docs so it is less confusing.
Added documentations for the new VO catalog and database functionalities and updated existing ones. Added VOSDatabase.list_catalogs_by_url() method and updated tests. Other code updates so examples work.
Use double ticks on change log as suggested by Erik Bray.
Edits by Ray Plante on VO manual (client.rst) for consistent use of 2nd person.