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

Change-Id: Ie0b78c79367933486528ca0ba686d4a9f16922b1
Pull-request: https://github.com/zzzeek/sqlalchemy/pull/370

local and remote columns.

An :class:`.ArgumentError` is now raised if a
:class:`.ForeignKeyConstraint` object is created with a mismatched
number of "local" and "remote" columns, which otherwise causes the
internal state of the constraint to be incorrect.   Note that this
also impacts the condition where a dialect's reflection process
produces a mismatched set of columns for a foreign key constraint.

Downstream DB2 dialect has been reported as potentially causing this
scenario.

Change-Id: Id51c34a6c43749bb582639f9c1dc28723482f0e5
Fixes: #3949
References: #3998

Added support for views that are unreflectable due to stale
table definitions, when calling :meth:`.MetaData.reflect`; a warning
is emitted for the table that cannot respond to ``DESCRIBE``
but the operation succeeds.  The MySQL dialect now
raises UnreflectableTableError which is in turn caught by
MetaData.reflect().  Reflecting the view standalone raises
this error directly.

Change-Id: Id8005219d8e073c154cc84a873df911b4a6cf4d6
Fixes: #3871

1. Sequence should be associated with MetaData always,
except in the really weird case someone is sharing a Sequence
among multiple metadatas.  Make this a "best practice", end the
confusion of #3951, #3979

2. "optional" is not a thing people use, trim this way down

3. remove confusing language

Change-Id: Iab5aec319da2582092fe2615ee50430f76441aff
(cherry picked from commit a1dcf23e371695d8d3be2e1d7875fad10f16a656)

which clarifies that ForeignKey circumvents this logic as a
"convenience".   issue #3978 is updated to address trying to make
this consistent.

Change-Id: I089acaa89f11b7a6310c2bf32916e26eb62ab9c0

will be cataloged in the .tables collection with its fully
qualified name.   Fixes #3978

Change-Id: I65fa063918efc22658e93c39a0680cb83553dec8

Fixed bug where a SQL-oriented Python-side column default could fail to
be executed properly upon INSERT in the "pre-execute" codepath, if the
SQL itself were an untyped expression, such as plain text.  The "pre-
execute" codepath is fairly uncommon however can apply to non-integer
primary key columns with SQL defaults when RETURNING is not used.

Tests exist here to ensure typing is applied to
a typed expression for default, but in the case of
an untyped SQL value, we know the type from the column,
so apply this.

Change-Id: I5d8b391611c137b9f700115a50a2bf5b30abfe94
Fixes: #3923