raise-or-decrease numbers in emacs-berlin

[Andreas Röhler]

Hi,

anyone interested to inaugurate the ar-add-to-number stuff as 
emacs-berlin package?

While it's basically some copy-and-paste from


https://github.com/andreas-roehler/werkstatt/blob/master/misc/misc-utils.el


it might be an interesting task WRT Emacs Lisp.


Maybe using raise/decrease would be a more suitable name?

As a bug showed up yesterday when decreasing, will contribute a related 
ert-test.

Cheers,


Andreas