python: work around old swig version
Swig 3.0.2 (currently installed by Debian), install strongly typed enumerator in the main namespace instead of in its own namespace. This is fixed in latter versions of Swig. * wrap/python/spot.py: If spot.op does not exists, populated it with all operators from the spot namespace. * wrap/python/tests/ltlsimple.py: Use operators from spot.op.