added ellipsis to make py3 greater-precision printing work...
Fix #1223 -- resource tags are not unnesting correctly on parsing.  Added test based on @RayPlante's example in #1223
Don't cause an exception during configuration file building if matplotlib is installed, but not Sphinx.
Simplify class comparison in tai_difference
docs update
moved link to References section
partial pep8ification; only whitespace modified
docstring / doctest fix attempt
Merge pull request #1223 from mdboom/votable/structure

Reading a VOTable with astropy does not get the table structure correct
moved ellipsis one character sooner
fix links
Simplified creating new models #980
WIP
reformatted docstring
Squashed commits implementing format argument, sans io/connect.py update

* 95592e1 Fix multiple registration problem for aliased formats
* 0889189 Redo the auto I/O registration in a more consistent way
* 178a2e4 Add table showing available ASCII I/O connector formats
* 331a69f Add auto-registration of readers/writers  (PARTIAL)
* d0841b1 Add format keyword to ascii.read and write methods
Update io.ascii.connect to provide functions for generic reader registration
Fix mistake in setting global FORMAT_CLASSES
Move info about IPAC position keyword into docstring
Using ascii. instead of ascii: to prefix ascii subformats
Shorten _description for fixedwidth_two_line slightly