Add no-heading option to the automodapi sphinx ext

This add the option to not have the auotmodapi extension add a top
level title, i.e `astropy.nddata Module`.
couple of docstring typos
Fix #819: Improve docs about ID/name to names/titles mapping
Speed up fk4_no_e_fk4 test.
Better use of __array_finalize__ and __array__ in quantity/longitude
Correct mistakes in use of wraps, views, and instances in CartesianPoint
(viz., __quantity_instance__, __quantity_view__, and __array_wrap__)
Add test cases for Quantity with record-array dtype
Expand comment on making scalars 0-dimensional arrays
Merge pull request #1841 from astrofrog/docs/fix-intersphinx

Fix Astropy intersphinx URL
Merge pull request #1884 from astrofrog/fix-xrange

Fix use of xrange with Python 3
Mention acceptable shortcut for `list(six.iterkeys(d))`
Fix instances of list(six.iterkeys(d))
Merge pull request #1893 from mdboom/misc/simplify-six

Fix some six changes
Fix Python 3 issue on big endian platforms
Add CHANGES entry
Merge pull request #819 from mdboom/vo/name-mapping-docs

Clarify docs on VOTable "name" and "id" vs. numpy "name" and "title"
Add Table pickling
Add tests of table and column pickling
Merge pull request #1848 from mhvk/quantity-improved-array-views

Better use of __array_finalize__ and __array__ in quantity/longitude/CartesianPoints
Add __setstate__ and __reduce__ methods so Columns can pickle