Collector #809: Added and documented Traversable.py methods absolute_url_path and virtual_url_path, and reverted earlier change to absolute_url behaviour.

- removed unused imports

consistent with changes in ZODB 3.3.

__roles__ attribute directly.  This further links the publisher to the
Zope application. :(

Perhsps in Zope 2.9, we can switch to using the Zope 3 publisher.

name.

prevent errors pickling acquisition wrappers from hiding the error the
test was looking for.

(special '__' methods) on an instance-by instance basis. Changed the
handling of the length so that the __len__ method looks for a __len__
dictionary key. It would be better not to use a __len__ attribute name
for the BTree length object, but such a change would be problematic
for old instances.

New-style class dictionaries are immutable. Changed some class-update
code to use setattr rather thah class-dictionary modifications.

__roles__ attribute.

validate method instead.

Use new getRoles function to get object roles, rather than using
__roles__ attribute.

Changed call to no-longer-supported validateValue methos to use the
validate method instead.

Use new getRoles function to get object roles, rather than using
__roles__ attribute.

New-style class dictionaries are immutable. Changed some class-update
code to use setattr rather thah class-dictionary modifications.

code to use setattr rather thah class-dictionary modifications.

followed by a security check.