character syntax fixes needed

[Dave Love]

The guillemets ‹, ›, « and » should all be punctuation.  The single
ones currently have word syntax, and the double ones are treated as
parens in latin-{1,5,9}.el.

Making Ÿ and ÿ a case pair in characters.el is clobbered by the entry
for code 255 in latin-1.el, which should presumably be removed.

The dotted-I and dotless-i case entries in characters.el are commented
out for some reason, and the new case-table functions introduced for
them aren't documented.