2014.10.18 MSS Code Factory 1.11.12466 Added Table ClearDep elements to engine

The ClearDep entries are essentially clones of the DelDep support, but they'll
be used differently in the rules.  Specifically, the last entry in the ClearDepChain
isn't used to identify a "ToTable", but to identify the relationship of the containing
table that needs to be cleared.

There were also errors in the rules for the clearing of sub-object references
from tables in the PostgreSQL code.  While the ClearDep support is a superset of
the sub-object reference clearing, the ClearDep support has to be explicitly stated
in the BAM, while the sub-object reference clearing is *inferred* from the model
automatically and therefore should be relied upon wherever possible to keep things
simple for the BAM author.

I will therefore continue on with applying the PostgreSQL rule changes to the other
databases rather than working on the use of the ClearDep specifications at this time.