Change-Id: I8172fdcc3103ff92aa049827728484c8779af6b7

Fixed bug in lambda SQL feature, used by ORM
:meth:`_orm.with_loader_criteria` as well as available generally in the SQL
expression language, where assigning a boolean value True/False to a
variable would cause the query-time expression calculation to fail, as it
would produce a SQL expression not compatible with a bound value.

Fixed issue where the :attr:`_orm.ORMExecuteState.is_relationship_load`
parameter would not be set correctly for many lazy loads, all
selectinloads, etc.  The flag is essential in order to test if options
should be added to statements or if they would already have been propagated
via relationship loads.

Fixes: #5763
Fixes: #5764
Change-Id: I66aafbef193f892ff75ede0670698647b7475482

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 deprecated logic to move order_by expressions
up into the columns clause needed adjustment to accommodate
for a more deeply-wrapped structure when desc() + label()
 are combined in an order by column.  This structure
now comes from coercions in 1.4.  it's not clear to me
at the moment why it's different from 1.3 but
this shouldn't really matter.

Fixes: #5443
Change-Id: If909a86f715992318d7aa283603197f7711f1d3b

This patch contains a variety of ORM and expression layer
tweaks to support ORM constructs in select() statements,
without the 1.3.x requiremnt in Query that a full
_compile_context() + new select() is needed in order to
get a working statement object.

Includes such tweaks as the ability to implement
aliased class of an aliased class,
as we are looking to fully support ACs against subqueries,
as well as the ability to access anonymously-labeled
ColumnProperty expressions within subqueries by
naming the ".key" of the label after the property
key.   Some tuning to query.join() as well
as ORMJoin internals to allow things to work more
smoothly.

Change-Id: Id810f485c5f7ed971529489b84694e02a3356d6d

This method might be used more significantly in the
ORM refactor, so further refine it.

* all get_children() methods now work entirely based on iterators.
  Basically only select() was sensitive to this anymore and it now
  chains the iterators together

* remove all kinds of flags like column_collections, schema_visitor
  that apparently aren't used anymore.

* remove the "depthfirst" visitors as these don't seem to be
  used either.

* make sure select() yields its columns first as these will be used
  to determine the current mapper.

Change-Id: I05273a2d5306a57c2d1b0979050748cf3ac964bf

The recipe given out on the ML for improving ABC
fails in 1.4 due to find_tables() missing out on subqueries,
which is due to the refactor of Alias into multiple sub-types.

Change-Id: Idd2803b26a84b28db28e0b8c328b8f24550577e4

Continuation of I408e0b8be91fddd77cf279da97f55020871f75a9

- add an options() method to the base Generative construct.
this will be where ORM options can go
- Change Null, False_, True_ to be singletons, so that
we aren't instantiating them and having to use isinstance.
The previous issue with this was that they would produce dupe
labels in SELECT statements.   Apply the duplicate column
logic, newly added in 1.4, to these objects as well as to
non-apply-labels SELECT statements in general as a means of
improving this.
- create a revised system for generating ClauseList compilation
constructs that simplfies up front creation to not actually
use ClauseList; a simple tuple is rendered by the compiler
using the same constrcution rules as what are used for
ClauseList but without creating the actual object.  Apply
to Select, CompoundSelect, revise Update, Delete
- Select, CompoundSelect get an initial CompileState
implementation.  All methods used only within compilation
are moved here
- refine update/insert/delete compile state to not require
an outside boolean
- refine and simplify Select._copy_internals
- rework bind(), which is going away, to not use some
of the internal traversal stuff
- remove "autocommit", "for_update" parameters from Select,
  references #4643
- remove "autocommit" parameter from TextClause ,
  references #4643
- add deprecation warnings for statement.execute(),
engine.execute(), statement.scalar(), engine.scalar().
Fixes: #5193

Change-Id: I04ca0152b046fd42c5054ba10f37e43fc6e5a57b

Created new visitor system called "internal traversal" that
applies a data driven approach to the concept of a class that
defines its own traversal steps, in contrast to the existing
style of traversal now known as "external traversal" where
the visitor class defines the traversal, i.e. the SQLCompiler.

The internal traversal system now implements get_children(),
_copy_internals(), compare() and _cache_key() for most Core elements.
Core elements with special needs like Select still implement
some of these methods directly however most of these methods
are no longer explicitly implemented.

The data-driven system is also applied to ORM elements that
take part in SQL expressions so that these objects, like mappers,
aliasedclass, query options, etc. can all participate in the
cache key process.

Still not considered is that this approach to defining traversibility
will be used to create some kind of generic introspection system
that works across Core / ORM.  It's also not clear if
real statement caching using the _cache_key() method is feasible,
if it is shown that running _cache_key() is nearly as expensive as
compiling in any case.    Because it is data driven, it is more
straightforward to optimize using inlined code, as is the case now,
as well as potentially using C code to speed it up.

In addition, the caching sytem now accommodates for anonymous
name labels, which is essential so that constructs which have
anonymous labels can be cacheable, that is, their position
within a statement in relation to other anonymous names causes
them to generate an integer counter relative to that construct
which will be the same every time.   Gathering of bound parameters
from any cache key generation is also now required as there is
no use case for a cache key that does not extract bound parameter
values.

Applies-to: #4639
Change-Id: I0660584def8627cad566719ee98d3be045db4b8d

Reworked the :meth:`.ClauseElement.compare` methods in terms of a new
visitor-based approach, and additionally added test coverage ensuring that
all :class:`.ClauseElement` subclasses can be accurately compared
against each other in terms of structure.   Structural comparison
capability is used to a small degree within the ORM currently, however
it also may form the basis for new caching features.

Fixes: #4336
Change-Id: I581b667d8e1642a6c27165cc9f4aded1c66effc6