- [bug] Fixed bug in 0.7.6 introduced by

- [bug] Fixed bug in 0.7.6 introduced by
[ticket:2409] whereby column_mapped_collection
used against columns that were mapped as
joins or other indirect selectables
would fail to function.

Here, the serialize use case has gotten very complex since to
really target a column we'd need the root MetaData object,
then if we're hitting Alias objects and such there's really
nothing to hold onto.  Short of building a system where
Column objects have some kind of master hash identifier that
is consistently generated, the way this works can't really
suit every case - much easier would be to change the mechanics
of collections.py to make available the Mapper to the
collection adapter when it's first invoked.