Add a mailmap

... for proper statistics (I thought I was #5 contributor at the
time I started the mailmap, but I was only #6).

Unfortunately, I could not find the full name of Stan
<goo.in.my.shoes@gmail.com> for proper credit.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Merge pull request #100 from dscho/mailmap

Add a mailmap