nipred.c, bug fix NIpred() when running 'TRAPEZOIDAL'

a long standing serious bug, allready in the very first commit from
  Date:   Thu Apr 27 20:03:57 2000 +0000

Nipred() after evaluating TRAPEZOIDAL case fell through into GEAR case.

see:
  http://sourceforge.net/p/ngspice/support-requests/18/

src/maths/ni/nipred.c

@@ -71,6 +71,9 @@ NIpred(CKTcircuit * ckt)
         default:
             return(E_ORDER);
         }
+    }
+    break;
+
     case GEAR: 
         node = ckt->CKTnodes;
         switch(ckt->CKTorder) {
@@ -137,8 +140,6 @@ NIpred(CKTcircuit * ckt)
         default:
             return(E_ORDER);
         }
-
-    }
     break;
 
     default: