Multi-entity constraints passed constraint.AddConstraintTableNoDelete will still be deleted when any entity other than the first one is deleted.

Fixes a bug where constraints that have been passed to `constraint.AddConstraintTableNoDelete` won't be deleted by the first entity being deleted, but will be deleted by any of the subsequent entities being deleted.
Merge pull request #480 from AbigailBuccaneer/master

constraint.AddConstraintTableNoDelete will still cause constraints to be deleted if the constraint is on multiple entities.