added, which proxies down to the ``.info`` attribute on either
the :class:`.schema.Column` object if directly present, or
the :class:`.MapperProperty` otherwise.  The full behavior
is documented and ensured by tests to remain stable.
[ticket:2675]

mapper configuration; will now test for name conflicts on
superclasses and subclasses, in addition to the current mapper,
as these conflicts break things just as much.  This is new for
0.8, but see below for a warning that will also be triggered
in 0.7.11.
- Improved the error message emitted when a "backref loop" is detected,
that is when an attribute event triggers a bidirectional
assignment between two other attributes with no end.
This condition can occur not just when an object of the wrong
type is assigned, but also when an attribute is mis-configured
to backref into an existing backref pair.  Also in 0.7.11.
- A warning is emitted when a MapperProperty is assigned to a mapper
that replaces an existing property, if the properties in question
aren't plain column-based properties.   Replacement of relationship
properties is rarely (ever?) what is intended and usually refers to a
mapper mis-configuration.   Also in 0.7.11.
[ticket:2674]

associated with the ORM or its extensions can be retrieved.
This fulfills the common request of being able to inspect
all :class:`.QueryableAttribute` descriptors in addition to
extension types such as :class:`.hybrid_property` and
:class:`.AssociationProxy`.  See :attr:`.Mapper.all_orm_descriptors`.

on regular append/remove history
- fix the real cause of the original #2637 issue, backrefs call upon
the "pop()" method now which wasn't implemented for Dynamic

- redefine inspect(Class.attrname).parent to be always an inspectable
target; either Mapper or AliasedInsp
- add most major features to 08 migration, document, link

  1. all Comparators now have "parent" which is always the parent mapper
  or AliasedClass instance

  2. only RelationshipProperty.Comparator has "mapper" now, which
  is the target mapper

  3. The names "parententity" and "parentmapper" are underscored

also improved the message with the "neither comparator nor instruentedattribute...."
to include the classname + attribute name