Check trivial multop equality at build time. The makes the

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/ltltest/parse.test

@@ -41,6 +41,7 @@ for f in \
   '()b' \
   'long_atomic_proposition_1 U long_atomic_proposition_2' \
   '  ab & ac | ad ^ af' \
+  '((b * a) + a) & d' \
   '(ab & ac | ad ) <=> af ' \
   'a U b U c U d U e U f U g U h U i U j U k U l U m' \
   '(ab * !Xad + ad U ab) & FG p12 & GF p13' \
@@ -55,7 +56,7 @@ do
   fi
 
   if test -n "$DOT"; then
-    ./ltl2dot "$f" > parse.dot 
+    ./ltl2dot "$f" > parse.dot
     if $DOT -o /dev/null parse.dot; then
       rm -f parse.dot
     else