Improve abbrev-completion.

   This amounts to a nearly-complete rewrite.
   From the improve-abbrev-completion branch.
* rgr-abbrev-completion.el:
   + (rgr-abbrev-kill):  Renamed from rgr-kill-last-symbol-abbreviation.
   + Content in save files written the same day is now merged.
   + Use lexical binding.
   + The code has also been modernized, and naming has been cleaned up.
* test/test-rgr-abbrev-completion.el:
   + Now with more thorough testing.
Fix string-to-number in rgr-perl-update-method-documentation

* rgr-perl-hacks.el:
   + (rgr-perl-update-method-documentation):  Oops; it's string-to-number
   + Also, use lexical binding.
Set up <f3> to run vm on a specified alternate mail folder

* rgr-mail-hacks.el:
   + (rgr-mail-alternate-folder):  Designated alternate VM folder.
   + (rgr-invoke-vm-alt-folder):  Run VM on rgr-mail-alternate-folder.
* rgr-hacks.el:
   + (rgr-install-function-keys):  If there's a modgen-consulting.vm
     folder, bind <f3> to run rgr-invoke-vm-alt-folder on it.
* rgr-elisp-hacks.el:  (rgr-make-tags-table-list-hook):  Add WebFrame
Handle subheads in Perl POD method doc

* rgr-perl-hacks.el:
   + (rgr-perl-update-method-documentation):  Bug fix:  Handle subheads
     within method documentation gracefully.  Previously, they would be
     treated as oddly-named methods, which fails when they sort badly.
Also predict the pumpernickel week after next

* rgr-pumpernickel.el:
   + (rgr-pump--make-prediction):  Pass in a title, do our own
     probability normalization. and fix the fill-paragraph so it works.
   + (rgr-alist-convolution):  Quick and dirty.
   + (rgr-show-pumpernickel-intervals):  Predict the next pumpernickel
     week, and the one after.
Add a pumpernickel histogram and make all predictions >=20%

* rgr-pumpernickel.el:
   + (rgr-pump--draw-histogram):  New ASCII-art hack.
   + (rgr-pump--make-prediction):  Split this out, show all weeks with
     at least 20% probability.
Add rgr-show-pumpernickel-intervals dates, use lexical binding

* rgr-pumpernickel.el:
   + (rgr-show-pumpernickel-intervals):  Add 13-Dec and 14-Feb.
   + Also add a provide form.
Fix parse-date hyphen handling

* parse-date.el:
   + (parse-date--tokenize-string):  Bug fix:  End the token only on
     only non-initial hyphens, and then be sure to skip over them.
* test/test-parse-date.el:
   + (parse-date-tests):  Add some hyphen (and other) tests.
Make parse-date &optional work, add basic testing

* parse-date.el:
   + (parse-date-2):  Rename the generic function from parse-date to
     parse-date-2 because &optional doesn't work with generics.
   + (parse-date):  The entrypoint is now an ordinary function with an
     &optional format argument.
* test/test-parse-date.el (added):
   + New test script, based on Emacs date parsing.
Add an umbrella test-rgr-hacks.el script

* test/test-rgr-hacks.el (added):
   + Umbrella test file, loads everything (though currently just one
     file) and runs all tests.
* makefile:
   + (test-rgr-hacks):  Replace the explicit "--batch --load" stuff with
     just the one test-rgr-hacks.el use.
Allow hyphens as parse-date token separators

* parse-date.el:
   + (parse-date--tokenize-string):  Bug fix:  Allow hyphens as token
     separators, being careful not to absorb them at the start of TZs.
Fix rgr-fill-sentence when point is between

* rgr-hacks.el:
   + (rgr-fill-sentence):  Bug fix:  Make this smarter when the original
     point is at the start or in between sentences.  Otherwise, we wind
     up filling both adjacent sentences.
Add the rgr-show-pumpernickel-intervals command

* rgr-pumpernickel.el (added):
   + (rgr-show-pumpernickel-intervals):  Use a bonehead-simple machine
     learning technique to predict the likely next week when my local
     bagel shop will have pumpernickel bagels as "bagel of the week."
* compile-rgr-hacks.el:
   + (rgr-hacks-source-files):  Compile rgr-pumpernickel.
Flush rgr-fill-rectangle

* rgr-hacks.el:
   + (rgr-fill-rectangle):  Not very useful; removed.
   + (rgr-install-global-editing-hacks):  Remove bindings.
New rgr-fill-sentence command

* rgr-hacks.el:
   + (rgr-fill-sentence):  New hack.
   + (rgr-install-global-editing-hacks):  Bind it to C-c q.
Remove unused shell get-old-input code

* rgr-shell-hacks.el:
   + (rgr-comint-get-old-input-with-continuation-lines):  Get rid of
     this, which apparently hasn't been used since 2008.
Flush v+q-sendmail-send-it

* vm+qmail.el:
   + (v+q-sendmail-send-it):  This is unused and almost certainly not
     needed any more.
   + (v+q-set-return-address):  Remove a ref to v+q-sendmail-send-it.
* emacs-init.el:
   + Remove a reference to sendmail-send-it in commented-out code.
* rgr-backup-hacks.el:  (rgr-update-backup-stars):  Removed.
Don't use debbugs-browse-url, plus other init file cleanup

* emacs-init.el:
   + Tweak browse-url-default-handlers to remove debbugs-browse-url for
     Emacs bugs.
   + Clean up obsolete ssh-host-history hosts.
   + Move the vm-mode init up with other vm stuff.