debian: also build with python3
We build with Python 3 along with Python 2. The binary package will
contain the extension for both python version. This is to ease
transition until the mercurial package in Debian uses Python 3. The
documentation is still built with Python 2 because it needs Mercurial
(which is currently Python 2).
syntax: re
/figures/[^/]+\.png$
^html/
\.pyc$
~$
\.swp$
\.orig$
\.rej$
^tests/.*\.err$
^tests/easy_run.sh$
^build/
^dist/
^MANIFEST$
^docs/tutorials/.*\.rst$
\.ico$
tests/\.testtimes
^docs/training/graphs/
^docs/training/html/
^docs/training/index.html
^docs/training/graphviz-images/
^docs/training/img/
^docs/training/output/
^docs/training/pandocfilters/