(Ara) Replace two 2-valued params in VP with one 3-valued param.

* is copula / is have_V2 / is neither

There is no difference; all three options are is mutually exclusive. 
There 2 params in the first place only by accident. First one was added 
by AED 10 years agon, second by me only some weeks ago, without thinking 
that the params are mutually exclusive.

Also tested with gftest, no difference found after 2 hours of running.

src/arabic/ResAra.gf

@@ -469,19 +469,25 @@ param
          | VPImp
          | VPGer ;
 
+  VType = -- indicates if there is a predicate (xabar): 
+          Copula  -- 1) disappears in equational sentences
+                  -- 2) its argument ('xabar') is in the pred field
+                  -- 3) it is negated with laysa
+         | Have   -- stays in eq. sentence, argument is in obj field, but is negated with laysa.
+         | NotPred ; -- any other verb but copula and have_V2
+
 oper
 
   BaseVP : Type = { -- to minimise duplication of code for VPS
     sc : Preposition ; -- subject case: e.g.  يُمْكِنُ *لِ*Xِ
     obj : Obj;
     pred : Comp;
-    isPred : Bool; -- indicates if there is a predicate (xabar)
+    vtype : VType ; -- copula, have_V2 or normal verb
     s2 : Str
     } ;
 
   VP : Type = BaseVP ** {
     s : PerGenNum => VPForm => Str ;
-    isPoss : Bool; -- special case for have_V2, to get negation right /IL
     } ;
 
   uttVP : VPForm -> VP -> (Gender=>Str) = \vpf,vp ->
@@ -502,7 +508,7 @@ oper
       obj = emptyObj ;
       s2 = [];
       pred = {s = \\_,_ => []} ;
-      isPred,isPoss = False
+      vtype = NotPred
     };
 
   passPredV : Verb -> VP = \v ->
@@ -543,18 +549,18 @@ oper
 
   bindIf : Bool -> Str = \b -> if_then_Str b BIND [] ;
 
-  bindIfPron : NP -> {c2:Preposition; isPred:Bool} -> Str = \np,vp ->
+  bindIfPron : NP -> {c2:Preposition; vtype:VType} -> Str = \np,vp ->
     let notNom : Case -> Bool = \c -> case c of {Nom => False; _=>True} ;
-        bind = case vp.isPred of {
-                 False => bindIf (
-                            orB (andB np.a.isPron (notNom vp.c2.c)) --if np is pron, not in nominative
-                                 vp.c2.binds) ;
-                 True  => [] }
+        bind = case vp.vtype of {
+                 Copula => [] ;
+                 _ => bindIf (orB (andB np.a.isPron (notNom vp.c2.c)) --if np is pron, not in nominative
+                                  vp.c2.binds)
+                 }
      in vp.c2.s ++ bind ++ np.s ! vp.c2.c ;
 
   insertPred : Comp -> VP -> VP = \p,vp -> vp **
     { pred = p;
-      isPred = True
+      vtype = Copula
     };
 
   insertStr : Str -> VP -> VP = \str,vp -> vp **
@@ -584,9 +590,9 @@ oper
                        _    => vp.sc }
               } ;
           subj = np.empty ++ sc.s ++ bindIf sc.binds
-              ++ case vp.isPred of {
-                    False => (proDrop np).s ! sc.c ; -- prodrop if it's not predicative
-                    True  =>           np.s ! sc.c
+              ++ case vp.vtype of {
+                    Copula =>      np.s ! sc.c ;
+                    _ => (proDrop np).s ! sc.c -- prodrop if it's not predicative
                  } ;
       in wordOrder o
            vp.obj.a.isPron np.a.isPron np.isHeavy
@@ -631,9 +637,9 @@ oper
 
   pred : VP -> PerGenNum -> ParamX.Tense -> Polarity -> Str = \vp,pgn,tn,pl ->
     let gn = pgn2gn pgn
-     in case <vp.isPred,tn,pl> of {
-          <True, Pres, Pos> => vp.pred.s ! gn ! Nom; --xabar marfooc
-          _                 => vp.pred.s ! gn ! Acc --xabar kaana wa laysa manSoob
+     in case <vp.vtype,tn,pl> of {
+          <Copula, Pres, Pos> => vp.pred.s ! gn ! Nom; --xabar marfooc
+          _                   => vp.pred.s ! gn ! Acc --xabar kaana wa laysa manSoob
         } ;
 
   vStr : VP -> PerGenNum -> ParamX.Tense -> Polarity -> Order -> Str = \vp,pgn,tn,pl,o ->
@@ -646,12 +652,12 @@ oper
         lam   = "لَمْ" ;   -- neg. past
         alla  = "أَلَّا" ; -- neg. subjunctive
         lan   = "لَنْ" ;   -- neg. future
-     in case <vp.isPred,tn,pl,o,vp.isPoss> of {
-          <False, Pres, Neg, _, True> => laysa ! Per3 Masc Sg ++ yaktubu ; -- special case for have_V2
-          <False, Pres, Pos, _> => yaktubu ;
-          <False, Pres, Neg, _> => la ++ yaktubu ;
-          <True, Pres, Pos, _> => [] ;    --no verb "to be" in present
-          <True, Pres, Neg, _> => laysa ! pgn ; -- negative copula
+     in case <vp.vtype,tn,pl,o> of {
+          <Have, Pres, Neg, _,> => laysa ! Per3 Masc Sg ++ yaktubu ; -- special case for have_V2
+          <Copula, Pres, Pos, _> => [] ;    --no verb "to be" in present
+          <Copula, Pres, Neg, _> => laysa ! pgn ; -- negative copula
+          <_, Pres, Pos, _> => yaktubu ;
+          <_, Pres, Neg, _> => la ++ yaktubu ;
           <_, Past, Pos, _> => kataba ;
           <_, Past, Neg, _> => lam ++ yaktub ;
           <_, Cond, Pos, _> => yaktuba ;
@@ -682,9 +688,9 @@ oper
   slashV2 : Verb2 -> VPSlash = \v ->
     predV v ** {
       c2 = v.c2 ; agrObj = \\_ => [] ;
-      isPoss = case v.c2.c of {
-                 Nom => True ; -- for have_V2
-                 _   => False } ;
+      vtype = case v.c2.c of {
+                 Nom => Have ; -- for have_V2
+                 _   => NotPred } ;
       } ;
 
   -- Add subject string, fix agreement to the subject,