reviewers:  these docs publish periodically at:
https://docs.sqlalchemy.org/en/gerrit/4042/orm/queryguide/index.html

See the "last generated" timestamp near the bottom of the
page to ensure the latest version is up

Change includes some other adjustments:

* small typing fixes for end-user benefit
* removal of a bunch of old examples for patterns that nobody
  uses or aren't really what we promote now
* modernization of some examples, including inheritance

Change-Id: I9929daab7797be9515f71c888b28af1209e789ff

Also replace http://pypi.python.org/pypi with https://pypi.org/project

Change-Id: I84b5005c39969a82140706472989f2a30b0c7685

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

remarkably, the examples for concrete and single were still
using classical mappings.    Ensure all three examples use
modern declarative patterns, each illustrate the identical set
of query operations.  Use back_populates, flat=True for joins,
etc. ensure flake8 linting, correct links and add a link back
from newly reworked inheritance documentation.

Change-Id: I8465a9badbb0eda804f457ccac599f051ee3c27c

to allow ad-hoc display of the source of any file, as well as a "directory listing" structure.
- reorganize examples/ to take advantage of new extension.  in particular, keep moving all
the descriptive text for files etc. into module docstrings, taking more advantage of
self-documentation.

- fix the targeting of module names moved around by using custom handlers for "Bases", etc.

- went through examples/ and cleaned out excess list() calls