2014.10.17 MSS Code Factory 1.10.12465 Add ClearDep to MSSBam 1.11. model

There needs to be a way of specifying that a relationship has to be cleared,
similar to the way sub-objects can be specified for deletion by a DelDep.
The only real-world case where this is needed so far is the CFBam 2.0
Relation.Narrowed specification, but one case is enough to force me to
support such a feature.  If I need it, I need it.  And odds are someone
else will need it someday.