・Rewrote Remark 2.3.3, (vi); added Figs. 2.5, 2.6; renumbered (and slightly modified the right-hand portion  of the third and sixth rows of) the subsequent "Fig." ・Slightly modified the phrasing of the first sentence of Remark 2.3.3, (vii) ・Rewrote various portions of Remark 2.3.3, (viii) ・Deleted the reference to Remark 2.3.3, (vi), in Theorem 3.11, (ii) ・Added Remark 3.11.4 and replaced the references to Remarks 2.3.2, 2.3.3 in the final portion of Theorem 3.11, (iii),  (c), (d), by references to Remark 3.11.4 ・Added Figs. 3.4, 3.5 and renumbered the subsequent "Figs."