this is from the writeonly patch, some doc edits became
more general so will backport these to 1.4.

Change-Id: I19231e4bcfa33a0742c8995b6059c9a9488b1a6f

This WIP is part of the final push for 1.4's docs
to fully "2.0-ize" what we can, and have it all ready.

So far this includes a rewrite of the 2.0 migration,
set up for the 1.4 /2.0 docs style, and a total redesign
of the index page using a new flex layout in zzzeeksphinx.

It also reworks some of the API reference sections
to have more subheaders.   zzzeeksphinx is also enhanced
to provide automatic summaries for all api doc section.

Change-Id: I01d360cb9c8749520246b96ee6496143c6037918

Reorganization of Select() is the first major element
of the 2.0 restructuring.   In order to start this we need
to first create the new Select constructor and apply legacy
elements to the old one.    This in turn necessitates
starting up the RemovedIn20Warning concept which itself
need to refer to "sqlalchemy.future", so begin to establish
this basic framework.   Additionally, update the
DML constructors with the newer no-keyword style.  Remove
the use of the "pending deprecation" and fix Query.add_column()
deprecation which was not acting as deprecated.

Fixes: #4845
Fixes: #4648
Change-Id: I0c7a22b2841a985e1c379a0bb6c94089aae6264c

Sphinx supports multiprocessing via the -j flag.  set to
auto so that multiple processes based on CPU core count
will be used.

Change-Id: Id89f860e0e113d670477b0322a7950281543d9d5

- to check for epub look at "builder"

  - https://readthedocs.org/projects/sqlalchemy/downloads/epub/latest/ renders with the full template which is unreadable on e-readers
  - in the makefile the template-variable mako_layout is set for target: epub which makes mako use only the base layout.
  - this is the more elegant solution as proposed to #133