el/dot-emacs.el: Sharpen up the page delimiter patterns.

el/dot-emacs.el: Sharpen up the page delimiter patterns.

The page-banner pattern is now much more precise: we need a brief
comment-opening sequence, up against the left margin, exactly five `-'s,
an optional heading surrounded by spaces, and then more `-'s to the end
of the line, with an optional short comment-closing sequence or knob.
I've not been especially picky about the comment opening and closing
sequences except that they should be short, but I don't think that will
be a problem.

We now need the `^L' to be at the start of the line.  The documentation
implies that Emacs already ensured this, but that's not true.