Added a new method :class:`.DefaultExecutionContext.current_parameters`
which is used within a function-based default value generator in
order to retrieve the current parameters being passed to the statement.
The new function differs from the ``.current_parameters`` attribute in
that it also provides for optional grouping of parameters that
correspond to a multi-valued "insert" construct.  Previously it was not
possible to identify the subset of parameters that were relevant to
the function call.

Change-Id: I6894c7b4a2bce3e83c3ade8af0e5b2f8df37b785
Fixes: #4075

Added ``__next__()`` and ``next()`` methods to :class:`.ResultProxy`,
so that the ``next()`` builtin function works on the object directly.
:class:`.ResultProxy` has long had an ``__iter__()`` method which already
allows it to respond to the ``iter()`` builtin.   The implementation
for ``__iter__()`` is unchanged, as performance testing has indicated
that iteration using a ``__next__()`` method with ``StopIteration``
is about 20% slower in both Python 2.7 and 3.6.

Change-Id: I70569a4c48ad85a3c21a7ad422f270a559926cfb
Fixes: #4077

Drops support for cx_Oracle prior to version 5.x, reworks
numeric and binary support.

Fixes: #4064

Change-Id: Ib9ae9aba430c15cd2a6eeb4e5e3fd8e97b5fe480

Added a new class of "rowcount support" for dialects that is specific to
when "RETURNING", which on SQL Server looks like "OUTPUT inserted", is in
use, as the PyODBC backend isn't able to give us rowcount on an UPDATE or
DELETE statement when OUTPUT is in effect.  This primarily affects the ORM
when a flush is updating a row that contains server-calcluated values,
raising an error if the backend does not return the expected row count.
PyODBC now states that it supports rowcount except if OUTPUT.inserted is
present, which is taken into account by the ORM during a flush as to
whether it will look for a rowcount.

ORM tests are implicit in existing tests run against PyODBC

Fixes: #4062
Change-Id: Iff17cbe4c7a5742971ed85a4d58660c18cc569c2

Made some adjustments to :class:`.Pool` and :class:`.Connection` such
that recovery logic is not run underneath exception catches for
``pool.Empty``, ``AttributeError``, since when the recovery operation
itself fails, Python 3 creates a misleading stack trace referring to the
``Empty`` / ``AttributeError`` as the cause, when in fact these exception
catches are part of control flow.

Change-Id: Id3ed9a8f96ce4ccb4009c94af30ddc2ddb9818b9
Fixes: #4028

Change-Id: Icb0474509539c1eb7536544749f2a48b4972078a
(cherry picked from commit 4ce46fb0a085c1cc739e21881cc25567e663f8dc)

Fixed bug where an index reflected under Oracle with an expression like
"column DESC" would not be returned, if the table also had no primary
key, as a result of logic that attempts to filter out the
index implicitly added by Oracle onto the primary key columns.

Reworked the "filter out the primary key index" logic in oracle
get_indexes() to be clearer.

This changeset also adds an internal check to ColumnCollection
to accomodate for the case of a column being added twice,
as well as adding a private _table argument to Index such that
reflection can specify the Table explicitly.  The _table
argument can become part of public API in a later revision
or release if needed.

Change-Id: I745711e03b3e450b7f31185fc70e10d3823063fa
Fixes: #4042

Added new keywords :paramref:`.Sequence.cache` and
:paramref:`.Sequence.order` to :class:`.Sequence`, to allow rendering
of the CACHE parameter understood by Oracle and PostgreSQL, and the
ORDER parameter understood by Oracle.  Pull request
courtesy David Moore.

Change-Id: I082c3f8ef56ef89dbaad5da9d5695be5313b0614
Pull-request: https://bitbucket.org/zzzeek/sqlalchemy/pull-requests/96

Added a new kind of :func:`.bindparam` called "expanding".  This is
for use in ``IN`` expressions where the list of elements is rendered
into individual bound parameters at statement execution time, rather
than at statement compilation time.  This allows both a single bound
parameter name to be linked to an IN expression of multiple elements,
as well as allows query caching to be used with IN expressions.  The
new feature allows the related features of "select in" loading and
"polymorphic in" loading to make use of the baked query extension
to reduce call overhead.   This feature should be considered to be
**experimental** for 1.2.

Fixes: #3953
Change-Id: Ie708414a3ab9c0af29998a2c7f239ff7633b1f6e