- fixed endless loop bug which could occur

- fixed endless loop bug which could occur
within a mapper's deferred load of
inherited attributes.
- declarative initialization of Columns adjusted so that
non-renamed columns initialize in the same way as a non
declarative mapper.   This allows an inheriting mapper
to set up its same-named "id" columns in particular
such that the parent "id" column is favored over the child
column, reducing database round trips when this value
is requested.