・Added Remark 2.4.2 ・Corrected misprints in the statement of Proposition 3.9, (i) ("compact open subsets" ---> "nonempty compact open subsets",  "compact closures of open subsets" ---> "compact closures of nonempty open subsets") ・Added Remark 3.9.7 ・Added Remark 3.10.2 ・Modified the final portion of Remark 3.11.1, (ii) ・Modified the discussion of "IPL" in Remark 3.11.1, (iii) ・Modified the final portion of Remark 3.11.1, (iii), and added a related reference to [IUTchII], Remark 1.9.2, to Remark 3.11.1, (iv) ・Modified the first paragraph of the proof of Corollary 3.12, and added a reference to this first paragraph to the discussion  immediately following the first display of Step (xi-b), as well as to the discussion immediately following the second display  of Step (xi-d) ・Slightly modified the wording (deleted the word "arbitrary") of the third display of Remark 3.12.2, (v)