* src/misc/bareword.cc, src/misc/bareword.hh (is_spin_ap): New function.
* src/ltlast/formula.cc, src/ltlast/formula.hh (is_spin_atomic_props):
New method and boolean.
* src/ltlast/atomic_prop.cc, src/ltlast/constant.cc: Update it.
* src/ltltest/kind.test: Test it.