hoa: fix handling of escaped characters in atomic propositions

* src/hoaparse/hoascan.ll: Remove superfluous line.
* src/tgbaalgos/hoaf.cc: Do not call to_string() to display names, as
this would add another level of escaping.
* src/tgbatest/hoaparse.test: Test it.

src/hoaparse/hoascan.ll

@@ -118,7 +118,6 @@ identifier  [[:alpha:]_][[:alnum:]_-]*
 			   yylval->str = new std::string(s);
 			   return token::STRING;
  			}
-  \\\"			s += '"';
   \\.			s += yytext[1];
   [^\\\"]+		s.append(yytext, yyleng);
   <<EOF>>		{

src/tgbaalgos/hoaf.cc

@@ -31,6 +31,7 @@
 #include "misc/minato.hh"
 #include "tgba/formula2bdd.hh"
 #include "ltlvisit/tostring.hh"
+#include "ltlast/atomic_prop.hh"
 
 namespace spot
 {
@@ -252,7 +253,11 @@ namespace spot
     auto d = aut->get_dict();
     for (metadata::vap_t::const_iterator i = md.vap.begin();
 	 i != md.vap.end(); ++i)
-      escape_str(os << " \"", to_string(d->bdd_map[*i].f)) << '"';
+      {
+	auto f = ltl::is_atomic_prop(d->bdd_map[*i].f);
+	assert(f);
+	escape_str(os << " \"", f->name()) << '"';
+      }
     os << nl;
     unsigned num_acc = aut->acc().num_sets();
     if (num_acc == 0)

src/tgbatest/hoaparse.test

@@ -456,7 +456,7 @@ States: 2
 Start: 0
 Start: 1
 Start: 0 /* duplicate */
-AP: 2 "a" "b"
+AP: 2 "a" "\"b\""
 Acceptance: 1 Inf(0)
 --BODY--
 State: 0 {0}
@@ -472,7 +472,7 @@ expectok input <<EOF
 HOA: v1
 States: 3
 Start: 0
-AP: 2 "a" "b"
+AP: 2 "a" "\"b\""
 acc-name: Buchi
 Acceptance: 1 Inf(0)
 properties: trans-labels explicit-labels state-acc complete