Escape parentheses with ~28 and ~29 in the anchor names of Scribble documents

External tools on the web often incorrectly delimit the
URLs used in Scribble anchors when it contains parens.  Mis-delimiting
the URL causes the link to break.  Jeff Atwood recommends escaping
parens as well that tools such as Wikipedia and Stack Overflow don't
fail so badly:
http://www.codinghorror.com/blog/2008/10/the-problem-with-urls.html