Extend the ELTL parser to support more complex aliases of

automaton operators such as Strong=G(F($0))->G(F($1)) and
G=R(false, $0).

* src/eltlparse/eltlparse.yy, src/eltlparse/eltlscan.ll: Add
support for more complex aliases.
* src/eltltest/acc.cc, src/eltltest/acc.test: Adjust.
* src/ltlast/nfa.cc, src/ltlast/nfa.hh (arity): Now returns an
unsigned value.
* src/tgbatest/eltl2tgba.test: Adjust.
* src/tgbalagos/eltl2tgba_lacim.cc: Fix sanity.

src/ltlast/nfa.cc

@@ -27,7 +27,7 @@ namespace spot
   namespace ltl
   {
     nfa::nfa()
-      : is_(), si_(), arity_(-1), name_(), init_(0), finals_()
+      : is_(), si_(), arity_(0), name_(), init_(0), finals_()
     {
     }
 
@@ -68,8 +68,8 @@ namespace spot
       t->dst = add_state(dst);
       t->label = label;
       s->push_back(t);
-      if (label > arity_)
-	arity_ = label;
+      if (label >= arity_)
+	arity_ = label + 1;
     }
 
     void
@@ -96,10 +96,10 @@ namespace spot
       return finals_.empty();
     }
 
-    int
+    unsigned
     nfa::arity()
     {
-      return arity_ + 1;
+      return arity_;
     }
 
     const nfa::state*

src/ltlast/nfa.hh

@@ -74,7 +74,7 @@ namespace spot
       bool is_loop();
 
       /// \brief Get the `arity' i.e. max t.cost, for each transition t.
-      int arity();
+      unsigned arity();
 
       /// \brief Return an iterator on the first succesor (if any) of \a state.
       ///