EAdded Remark 3.3.1, as well as a reference to this remark in the statement of Proposition 3.4, (ii)
ERewrote Definition 4.7 and Theorem 4.8, (i), and made corresponding modifications to the proofs of Theorem 4.8, (i), (ii)
@(i.e., in essence, restored the October versions of these portions of the paper)
EAdded Remark 4.7.1, as well as references to this remark in Definition 4.7 and the proof of Theorem 4.8, (i)