The scalar object set() method calls upon the lazy loader
to get at the "old" value of the attriute, however doesn't
ensure that the "committed" value of the foreign key attributes
is used.  If the user has manipulated these attributes and they
themselves have pending, non committed changes, we get the
"new" value which these attributes would have set up if they
were flushed.  "old" vs "new" value is always about how the
value has changed since the load, so we always have to use the
DB-persisted values for everything when looking for "old".

Change-Id: I82bdc40ad0cf033c3a98f3361776cf3161542cd6
Fixes: #3708

This allows us to build default-setting recipes such
as one that allows us to actively read column-level
defaults.  An example suite is also added.

Change-Id: I7b022d52cc89526132d5bc4201ac27fea4cf088d
Fixes: #1311

Includes removal of adapt_like_to_iterable() as well
as _set_iterable(), uses __slots__ for collectionadapter,
does much less duck typing of collections.

to function for a many-to-one relationship.  The loader used an
API to place "None" into the dictionary which no longer actually
writes a value; this is a side effect of :ticket:`3061`.
- remove InstanceState._initialize() totally, it's used nowhere
else and no longer does what it says it does
- fill in fowards-port version ids throughout the changes for 1.0.9

to transient objects with attributes unset would leak NEVER_SET,
and negated_contains_or_equals would do so for any transient
object as the comparison used only the committed value.
Repaired the NEVER_SET cases, fixes #3371, and also made
negated_contains_or_equals() use state_attr_by_column() just
like a non-negated comparison, fixes #3374

in callcounts specific to the "expiration" of objects, as in
the "auto expire" feature of :meth:`.Session.commit` and
for :meth:`.Session.expire_all`, as well as in the "cleanup" step
which occurs when object states are garbage collected.
fixes #3307

size of the many per-column objects we're hitting, but somehow the overall memory is
hardly being reduced at all in initial testing