- using contains_eager() against an alias combined with an overall query alias repair...

- using contains_eager() against an alias combined with an overall query alias repaired - the
contains_eager adapter wraps the query adapter, not vice versa.  Test coverage added.
- contains_eager() will now add columns into the "primary" column collection within Query._compile_context(), instead
of the "secondary" collection.  This allows those columns to get wrapped within the subquery generated
by limit/offset in conjunction with an ORM-generated eager join.
Eager strategy also picks up on context.adapter in this case to deliver the columns during result load.
contains_eager() is now compatible with the subquery generated by a regular eager load
with limit/offset. [ticket:1180]