equal visitor useless, since two equals formulae will now
share the same address.
* src/ltlast/multop.hh (add_sorted): New function.
(paircmp): New comparison functor.
(map): Use paircmp, we want to compare the vectors' contents,
not their addresses.
* src/ltlast/multop.cc (add_sorted): New function.
(add): Use it.
* src/ltltest/equals.cc, src/ltltest/tostring.cc: Compare
pointers instead of calling equal.
* src/ltlvisit/equals.cc, src/ltlvisit/equals.hh: Delete.
* src/ltlvisit/Makefile.am (libltlvisit_la_SOURCES): Remove
equals.cc and equals.hh.
* wrap/spot.i: Do not include equals.hh.
* src/ltlast/atomic_prop.hh: Declare instance_count().
* src/ltlast/binop.hh, src/ltlast/unop.hh, src/ltlast/multop.hh:
Likewise. Also, really inherit for ref_formula this time.
* src/ltlast/atomic_prop.cc, src/ltlast/binop.cc,
src/ltlast/unop.cc, src/ltlast/multop.cc: On destruction, suppress
the instance from the instance map. Implement instance_count().
* src/ltlast/formula.cc, src/ltlast/formula.hh,
src/ltlast/ref_formula.cc, src/ltlast/ref_formula.hh: Add virtual
destructors.
* src/ltlparse/ltlparse.yy: Recover from binary operators with
missing right hand operand (the point is just to destroy the
the left hand operand).
* src/ltltest/equals.cc, src/ltltest/readltl.cc,
src/ltltest/tostring.cc: Destroy used formulae. Make sure
instance_count()s are null are the end.
* src/ltltest/parseerr.test: Adjust expected result, now
that the parser lnows about missing right hand operands.
* src/ltlvisit/destroy.hh, src/ltlvisit/destroy.cc,
src/ltlvisit/postfix.hh, src/ltlvisit/postfix.cc: New files.
* src/ltlvisit/Makefile.am (libltlvisit_la_SOURCES): Add them.
* src/ltlvisit/lunabbrev.cc (Xor, Equiv): Clone formulae
occurring twice in the rewritten expression.
spot::ltl:: prefixes.
(to_string(formula)): New function.
* src/ltlvisit/tostring.hh (to_string(formula)): Likewise.
* src/ltltest/tostring.cc: Use this new to_string function to
simplify.
description of the test ...
* src/ltltest/tostring.cc: ... here, where it is actually coded.
* src/ltltest/lunabbrev.test, src/ltltest/tunabbrev.test,
src/ltltest/nenoform.test, src/ltltest/tunenoform.test:
Simplify with set -e.
* src/ltltest/tostring.cc: New files.
* src/ltlvisit/tostring.hh: From ast to string New files.
* src/ltlvisit/tostring.cc: From ast to string New files.
