remove support for confusing manipulation of $VAR

C/c_interface.c

@@ -3652,7 +3652,7 @@ Term YAP_UnNumberVars(Term t) {
 }
 
 int YAP_IsNumberedVariable(Term t) {
-  return IsApplTerm(t) && FunctorOfTerm(t) == FunctorVar &&
+  return IsApplTerm(t) && FunctorOfTerm(t) == FunctorDollarVar &&
          IsIntegerTerm(ArgOfTerm(1, t));
 }
 

C/userpreds.c

@@ -558,7 +558,7 @@ static int p_grab_tokens() {
   char ch, IdChars[256], *chp;
 
   IdFunctor = FunctorId;
-  VarFunctor = FunctorVar;
+  VarFunctor = FunctorDollarVar;
   p0 = p;
   ch = Yap_PlGetchar();
   while (1) {

C/utilpreds.c

@@ -4584,7 +4584,7 @@ numbervar(Int id USES_REGS)
 {
   Term ts[1];
   ts[0] = MkIntegerTerm(id);
-  return Yap_MkApplTerm(LOCAL_FunctorVar, 1, ts);
+  return Yap_MkApplTerm(FunctorDollarVar, 1, ts);
 }
 
 static Term
@@ -4592,7 +4592,7 @@ numbervar_singleton(USES_REGS1)
 {
   Term ts[1];
   ts[0] = MkIntegerTerm(-1);
-  return Yap_MkApplTerm(LOCAL_FunctorVar, 1, ts);
+  return Yap_MkApplTerm(FunctorDollarVar, 1, ts);
 }
 
 static void
@@ -4904,7 +4904,7 @@ unnumber_complex_term(CELL *pt0, CELL *pt0_end, CELL *ptf, CELL *HLow, int share
 	  *ptf++ = d0;  /* you can just unnumber other extensions. */
 	  continue;
 	}
-	if (f == FunctorVar) {
+	if (f == FunctorDollarVar) {
 	  Int id = IntegerOfTerm(ap2[1]);
 	  ground = FALSE;
 	  if (id < -1) {

C/write.c

@@ -1117,14 +1117,17 @@ static void writeTerm(Term t, int p, int depth, int rinfixarg,
       if (op > p) {
         wrclose_bracket(wglb, TRUE);
       }
-    } else if (wglb->Handle_vars && functor == LOCAL_FunctorVar) {
+    } else if ( functor == FunctorDollarVar) {
       Term ti = ArgOfTerm(1, t);
       if (lastw == alphanum) {
         wrputc(' ', wglb->stream);
       }
-      if (!IsVarTerm(ti) &&
-          (IsIntTerm(ti) || IsCodesTerm(ti) ||
-	   IsAtomTerm(ti) || IsStringTerm(ti) )) {
+      if (wglb->Handle_vars &&
+          !IsVarTerm(ti) &&
+          (IsIntTerm(ti) ||
+           IsCodesTerm(ti) ||
+           IsAtomTerm(ti) ||
+           IsStringTerm(ti) )) {
         if (IsIntTerm(ti)) {
           Int k = IntOfTerm(ti);
           if (k == -1) {