Merge: Check contrib

Add a script `misc/jenkins/check_contrib.sh` to automatically compile and tests things in contrib and examples.

New (and existing) programs in these directory should try to add some basic (or extensive) checking.

Note that I used the name `check` that is the standard name for Makefiles (`tests` seems to be an invention of myself) http://www.gnu.org/software/make/manual/make.html#Standard-Targets

Pull-Request: #1259
Reviewed-by: Alexis Laferrière <alexis.laf@xymus.net>