A few more edits and additions

Found a few more edits in the book, fixed them, and added a couple of new pages.  Changelog:

• Page 13: Editing in the second half; language reference an old 'build'.
• Page 16: This is an entirely new page on fill-in-blank skills; the previous page 16 is moved to later (see below).
• Pages 17 + 19: Options and minor rules paragraphs tagged on at end of page.
• Pages 34 - 39: Examples edited to take out the "well-equipped" references (old build; that's an optional rule)
• Pages 56-59: Additional "Delver" character creation added, if you want to get strength/dexterity/constitutiony about it.

A delver-style character sheet has also been uploaded.