ORM attributes can now be assigned any object that is has a
``__clause_element__()`` attribute, which will result in inline
SQL the way any :class:`.ClauseElement` class does.  This covers other
mapped attributes not otherwise transformed by further expression
constructs.

As part of this, it was considered that we could add
__clause_element__() to ClauseElement, however this causes endless loops
in a "while" pattern and this pattern has been identified in third
party libraries.  Add a test to ensure we never make that change.

Change-Id: I9e15b3f1c4883fd3909acbf7dc81d034c6e3ce1d
Fixes: #3802

Added compiler-level flags used by Postgresql to place additional
parenthesis than would normally be generated by precedence rules
around operations involving JSON, HSTORE indexing operators as well as
within their operands since it has been observed that Postgresql's
precedence rules for at least the HSTORE indexing operator is not
consistent between 9.4 and 9.5.

Fixes: #3806
Change-Id: I5899677b330595264543b055abd54f3c76bfabf2

A string sent as a column default via the
:paramref:`.Column.server_default` parameter is now escaped for quotes.

This change is backwards compatible with code that may have been
working around this previously.

Change-Id: I341298a76cc67bc0a53df4ab51ab9379f2294cdd
Fixes: #3809

The "eq" and "ne" operators are no longer part of the list of
"associative" operators, while they remain considered to be
"commutative".  This allows an expression like ``(x == y) == z``
to be maintained at the SQL level with parenthesis.  Pull request
courtesy John Passaro.

Fixes: #3799
Change-Id: I3759d8987b35649d7418b6524316c9e70c857e68
Pull-request: https://github.com/zzzeek/sqlalchemy/pull/308

Fixes the comparison of bindparam() objects based on
the "callable" parameter being present which helps to correctly
detect use_get, and also checks for "callable" when detecting
parameters for value substitution and will not impact the
object if present.

Change-Id: I4c93ee5d404d2648dd9835beeae0c5fb67e37d19
Fixes: #3767

Fixed bug where setting up a single-table inh subclass of a joined-table
subclass which included an extra column would corrupt the foreign keys
collection of the mapped table, thereby interfering with the
initialization of relationships.

Change-Id: I04a0cf98fd456d12d5a5b9e77a46a01246969a63
Fixes: #3797

Fixed bug where the "simple many-to-one" condition that allows  lazy
loading to use get() from identity map would fail to be  invoked if the
primaryjoin of the relationship had multiple clauses separated by AND
which were not in the same order as that of the primary key columns
being compared in each clause. This ordering
difference occurs for a composite foreign key where the table-bound
columns on the referencing side were not in the same order in the .c
collection as the primary key columns on the referenced side....which
in turn occurs a lot if one is using declarative mixins and/or
declared_attr to set up columns.

Change-Id: I66cce74f614c04ed693dc0d58ac8c952b2f8ae54
Fixes: #3788

Stringify of expression with unnamed :class:`.Column` objects, as
occurs in lots of situations including ORM error reporting,
will now render the name in string context as "<name unknown>"
rather than raising a compile error.

Change-Id: I76f637c5eb4cfdb1b526964cb001565b97e296da
Fixes: #3789