・Modified the year ("1991 ---> 2010") for the Mathematics Subject Classification ・Corrected a misprint in the second display of Example 0.3 ・Deleted unnecessary "i.e.'s" in the statement of Lemma 1.5, (vi) (1 instance); the statement of Lemma 1.5, (viii) (1 instance); the second paragraph of the proof of Proposition 2.3, (iii) (3 instances); the sixth paragraph of the proof of Proposition 3.2, (v) (1 instance) ・Corrected a misprint in the first paragraph of the proof of Proposition 2.3 ("the the" ---> "the", 2 instances) ・Deleted an unnecessary "Thus," in Definition 3.1, (ii) ・Corrected a misprint in the fifth paragraph of the proof of Proposition 3.2, (v) ("suscheme" ---> "subscheme") ・Corrected a misprint in Remark 3.7.1 ("corrected" ---> "correct") ・Rewrote Definition 4.7 and Theorem 4.8, (i), and made corresponding modifications to the proofs of Theorem 4.8, (i), (ii) ・Added references to the "[final] surjectivity portion" of [LgSch], Proposition 2.6, (ii), to Fig. 1 and the preceding  discussion ・Added an explanatory phrase ("via a direct reference") to the discussion of the fourth columns of Figs. 1 and 2 in the  Appendix ・Modified the portion of Fig. 1 concerning 2.13 ・Added the URL for the homepage of the preprint referred to in the Appendix ・Modified the portion of Fig. 2 concerning C4.3 ・Modified the portion of Fig. 2 and the surrounding discussion concerning L5.1, L5.2 ・Corrected a misprint in the e-mail address and slightly modified the format of the university address given at the end  of the paper