[emacs-w3m:13666] Update to w3m-history-scrub (PR#2)

I just now pushed an update to my proposal for a history-scrub feature
for emacs-w3m, similar to what is standard on all modern browsers. I've
been using this successfully without incident for more than 18 months
now, but I wanted a feature to optionally add anything to scrub, via a
configuration variable, so that's now in module.

On github, it exists as ye olde pull request #2 for the 'official' emacs-w3m
version, and on my fork you can see it on the master branch. If you want
to use it with the 'official' version, it might be sufficient to
download my version of file `w3m-hist.el' and evaluate these:

   defvar w3m-scrub-command-list
   defvar w3m-history-scrub-optional-elements
   defun w3m-history-scrub

You'll also need to either evaluate from my version of file `w3m.el'
this function:

   defun w3m--full-window-message

Or you can manually disable or replace the warning message from defun
w3m-history-scrub.

--
hkp://keys.gnupg.net
CA45 09B5 5351 7C11 A9D1  7286 0036 9E45 1595 8BC0