The ORM Declarative system is now unified into the ORM itself, with new
import spaces under ``sqlalchemy.orm`` and new kinds of mappings.  Support
for decorator-based mappings without using a base class, support for
classical style-mapper() calls that have access to the declarative class
registry for relationships, and full integration of Declarative with 3rd
party class attribute systems like ``dataclasses`` and ``attrs`` is now
supported.

Fixes: #5508
Change-Id: I130b2b6edff6450bfe8a3e6baa099ff04b5471ff

This change includes mainly that the bracketed use within
select() is moved to positional, and keyword arguments are
removed from calls to the select() function.  it does not
yet fully address other issues such as keyword arguments passed
to the table.select().

Additionally, allows False / None to both be considered
as "disable" for all of select.correlate(), select.correlate_except(),
query.correlate(), which establishes consistency with
passing of ``False`` for the legact select(correlate=False)
argument.

Change-Id: Ie6c6e6abfbd3d75d4c8de504c0cf0159e6999108

The name of the virtual column used when using the
:class:`_declarative.AbstractConcreteBase` and
:class:`_declarative.ConcreteBase` classes can now be customized, to allow
for models that have a column that is actually named ``type``.  Pull
request courtesy Jesse-Bakker.

Fixes: #5513
Closes: #5514
Pull-request: https://github.com/sqlalchemy/sqlalchemy/pull/5514
Pull-request-sha: 5e7429f3531e2e22fffe996c9760905578d16ef9

Change-Id: I733737844d4f4e1f52dd2475a66c7044ff7292f5

The commit for I1654befe9eb1c8b8e7fc0784bdbe64284614f0ea #5357
runs the test on all Python 3 versions, however we need to limit
at least python 3.6 for this.

Change-Id: Ie86b78bbfd8c7bd013ff9aa7f8905328d792c1b3

Added a ``**kw`` argument to the :meth:`.DeclarativeMeta.__init__` method.
This allows a class to support the :pep:`487` metaclass hook
``__init_subclass__``.  Pull request courtesy Ewen Gillies.

Fixes: #5357
Closes: #5363
Pull-request: https://github.com/sqlalchemy/sqlalchemy/pull/5363
Pull-request-sha: 0ad05a768316cba03a4d312ab39d3e8fbca7ac54

Change-Id: I1654befe9eb1c8b8e7fc0784bdbe64284614f0ea

towards the goal of reducing verbosity and repetition
in test fixtures as well as that we are moving to
connection only for execution, move the insert_data()
classmethod to accept a connection and adjust all
fixtures to use it.

Change-Id: I3bf534acca0d5f4cda1d4da8ae91f1155b829b09

The string argument accepted as the first positional argument by the
:func:`.relationship` function when using the Declarative API is no longer
interpreted using the Python ``eval()`` function; instead, the name is dot
separated and the names are looked up directly in the name resolution
dictionary without treating the value as a Python expression.  However,
passing a string argument to the other :func:`.relationship` parameters
that necessarily must accept Python expressions will still use ``eval()``;
the documentation has been clarified to ensure that there is no ambiguity
that this is in use.

Fixes: #5238
Change-Id: Id802f403190adfab0ca034afe2214ba10fd9cfbb

Also remove no longer used compat code

Change-Id: Ifda239fd84b425e43f4028cb55a5b3b8efa4dfc6

Introduced a modules registry to register modules that should be lazily loaded
in the package init. This ensures that they are in the system module cache,
avoiding potential thread safety issues as when importing them directly
in the function that uses them. The module registry is used to obtain
these modules directly, ensuring that the all the lazily loaded modules
are resolved at the proper time

This replaces dependency_for decorator and the dependencies decorator logic,
removing the need to pass the resolved modules as arguments of the
decodated functions and removes possible errors caused by linters.

Fixes: #4689
Fixes: #4656
Change-Id: I2e291eba4297867fc0ddb5d875b9f7af34751d01

Enhanced logic that tracks if relationships will be conflicting with each
other when they write to the same column to include simple cases of two
relationships that should have a "backref" between them.   This means that
if two relationships are not viewonly, are not linked with back_populates
and are not otherwise in an inheriting sibling/overriding arrangement, and
will populate the same foreign key column, a warning is emitted at mapper
configuration time warning that a conflict may arise.  A new parameter
:paramref:`.relationship.overlaps` is added to suit those very rare cases
where such an overlapping persistence arrangement may be unavoidable.

Fixes: #5171
Change-Id: Ifae5998fc1c7e49ce059aec8a67c80cabee768ad