Test python bindings including import.

tests/build.sh

@@ -8,3 +8,4 @@ python3 -c "import setuptools; print(setuptools.__name__, 'version', setuptools.
 echo "##############################################"
 python3 setup.py build_ext --inplace
 cp prrt*.so ./build/
+python3 -c "import sys; sys.path.insert(0, './build'); import prrt"