Replaces a wide array of Sphinx-relative doc references
with an abbreviated absolute form now supported by
zzzeeksphinx.

Change-Id: I94bffcc3f37885ffdde6238767224296339698a2

As we are going to be adding a lot of new features to the visitors
module which may impact end-user custom constructs, start documenting
the package for now.

Change-Id: Ibae471c2cb861f6280f601b7b2382d61968825cd
(cherry picked from commit ed02d924dd0bd1bce56b40bea74e1d382c352833)

Change-Id: I6a71f4924d046cf306961c58dffccf21e9c03911
(cherry picked from commit 6f270fb0e344016ce526e0a1ecb3e3de9ffd1e3b)

Applied on top of a pure run of black -l 79 in
I7eda77fed3d8e73df84b3651fd6cfcfe858d4dc9,  this set of changes
resolves all remaining flake8 conditions for those codes
we have enabled in setup.cfg.

Included are resolutions for all remaining flake8 issues
including shadowed builtins, long lines, import order, unused
imports, duplicate imports, and docstring issues.

Change-Id: I4f72d3ba1380dd601610ff80b8fb06a2aff8b0fe

This is a straight reformat run using black as is, with no edits
applied at all.

The black run will format code consistently, however in
some cases that are prevalent in SQLAlchemy code it produces
too-long lines.   The too-long lines will be resolved in the
following commit that will resolve all remaining flake8 issues
including shadowed builtins, long lines, import order, unused
imports, duplicate imports, and docstring issues.

Change-Id: I7eda77fed3d8e73df84b3651fd6cfcfe858d4dc9

Change-Id: I3ef36bfd0cb0ba62b3123c8cf92370a43156cf8f

After bump minimum supported version to 2.7 (1da9d3752160430c91534a8868ceb8c5ad1451d4), we can use new syntax.

Change-Id: Ib064c75a00562e641d132f9c57e5e69744200e05
Pull-request: https://github.com/zzzeek/sqlalchemy/pull/347

Change-Id: I4e8c2aa8fe817bb2af8707410fa0201f938781de