* src/ltltest/inf.test: More test.
* src/ltlvisit/basereduc.cc, src/ltlvisit/forminf.cc (spot):
Use dynamic_cast.
* src/ltlvisit/reducform.cc, src/ltlvisit/reducform.hh,
src/ltltest/reduc.test, src/ltltest/reduc.cc: Add an option
to choose which rules applies to simplify the formula.