* Highlights both 1st level and 2nd level quotes and signatures.
* This also sets the edge to 78 columns, as is recommended for email and
  enables word wrapping.
  The edge mode is not set, since it kind of looks ugly in Scinterm.
* Helps when using SciTECO as the email editor for instance in the
  Aerc mail client.
* Unfortunately, we cannot set up Scintilla to automatically break words
  after 78 columns (or perhaps that's a good thing).
  You can use the M#rf reformat-paragraph macro to reflow paragraphs
  before sending the mail.
  This will take the edge column into account even if no edge mode is set.