* src/twaalgos/safety.cc, src/twaalgos/safety.hh: Rename as ...
* src/twaalgos/strength.cc, src/twaalgos/strength.hh: ... these.
* src/bin/ltlfilt.cc, src/tests/ikwiad.cc, src/twaalgos/Makefile.am,
src/twaalgos/compsusp.cc, src/twaalgos/minimize.cc,
wrap/python/spot_impl.i: Adjust.