Use the system monospace font in the docs
Allow for custom datatype names in votable

This should allow end users to workaround VOTable files that contain
invalid datatypes.

Also adds two datatypes seen in Vizier tables: "unsignedInt" and "unsignedShort".
Update docs about datatype mappings.
Add changes entry.
Implementation of wcs_to_celestial_frame
Minor improvements
Make wcs_to_celestial_frame extensible
Added tests and docstring for ``wcs_to_celestial_frame``
Skip doctest
Added changelog entry
typo fix: arcseconds->milliarcseconds


[ci skip]
Expand locale known issue
Merge pull request #2760 from astrofrog/more-known-issues

Expand locale known issue
Describe bounds checking at toplevel of docs.
Fix formatting error that causes PDF/LaTeX docs to not finish.
Don't put all user documentation under the "what's new" heading in LaTeX docs.
Merge pull request #2763 from mdboom/wcs/bounds-check-doc

astropy.wcs returns nan when galactic longitude >= 180 degrees
Merge pull request #2764 from mdboom/docs/latex-fixes

LaTeX doc build fixes
Fix the test for an unedited astropy 0.3.2 config

Ignore the jquery_url line when calculating md5sum.
Modernize jsviewer configuration items.