templates/filters: add doctest to the 'person' filter
Add a doctest with an hopefuly-comprehensive list of combinations
we can expect in real-life situations.
This does not cover corner cases, for example when a CR or LF is
embedded in the name (allowed by RFC 5322!).
Code in tests/test-doctest.py contributed by:
Martin Geisler <mg@aragost.com>
Thanks!
Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>