devices/bjt/bjttemp.c, bug fix, capacity temperature dependency

Fix a very old bug in the implementation of the
  gummel-poon model formulas for the junction capacities.
  (already in spice3f4)
For unknown reasons, the same formulas in the
  diode mos1 mos2 mos6 jfet models
have been implemented correctly right from the beginning,
the typo was bjt specific.

Many Thanks for the concise and precise Bug Report
  provided by Schabo Rumanus on the ngspice-users mailing list
> To: ngspice-users@lists.sourceforge.net
> Subject: [Ngspice-users] Temperatursimulation von Sperrschichtkapazitäten

Many Thanks to Dietmar Warning for his thorough verification
  of this commit.

src/spicelib/devices/bjt/bjttemp.c

@@ -24,6 +24,7 @@ BJTtemp(GENmodel *inModel, CKTcircuit *ckt)
     BJTinstance *here;
     double xfc;
     double vt;
+    double vtnom;
     double ratlog;
     double ratio1;
     double factlog;
@@ -40,6 +41,7 @@ BJTtemp(GENmodel *inModel, CKTcircuit *ckt)
     for( ; model != NULL; model = model->BJTnextModel ) {
 
         if(!model->BJTtnomGiven) model->BJTtnom = ckt->CKTnomTemp;
+        vtnom = CONSTKoverQ * model->BJTtnom;
         fact1 = model->BJTtnom/REFTEMP;
 
         if(!model->BJTleakBEcurrentGiven) {
@@ -101,6 +103,7 @@ BJTtemp(GENmodel *inModel, CKTcircuit *ckt)
         for (here = model->BJTinstances; here != NULL ;
                 here=here->BJTnextInstance) {
 
+            double arg1, pbfact1, egfet1;
             if(!here->BJTdtempGiven)
                 here->BJTdtemp = 0.0;
 
@@ -162,6 +165,11 @@ BJTtemp(GENmodel *inModel, CKTcircuit *ckt)
             arg = -egfet/(2*CONSTboltz*here->BJTtemp)+
                     1.1150877/(CONSTboltz*(REFTEMP+REFTEMP));
             pbfact = -2*vt*(1.5*log(fact2)+CHARGE*arg);
+            egfet1 = 1.16-(7.02e-4*model->BJTtnom*model->BJTtnom)/
+                    (model->BJTtnom+1108);
+            arg1 = -egfet1/(2*CONSTboltz*model->BJTtnom)+
+                    1.1150877/(CONSTboltz*(REFTEMP+REFTEMP));
+            pbfact1 = -2*vtnom*(1.5*log(fact1)+CHARGE*arg1);
 
             ratlog = log(here->BJTtemp/model->BJTtnom);
             ratio1 = here->BJTtemp/model->BJTtnom -1;
@@ -200,7 +208,7 @@ BJTtemp(GENmodel *inModel, CKTcircuit *ckt)
             }
 
             if (model->BJTtlevc == 0) {
-                pbo = (model->BJTpotentialBE-pbfact)/fact1;
+                pbo = (model->BJTpotentialBE-pbfact1)/fact1;
                 gmaold = (model->BJTpotentialBE-pbo)/pbo;
                 here->BJTtBEcap = model->BJTdepletionCapBE/
                     (1+here->BJTtjunctionExpBE*
@@ -215,7 +223,7 @@ BJTtemp(GENmodel *inModel, CKTcircuit *ckt)
                 here->BJTtBEpot = model->BJTpotentialBE - model->BJTtvje*dt;
             }
             if (model->BJTtlevc == 0) {
-                pbo = (model->BJTpotentialBC-pbfact)/fact1;
+                pbo = (model->BJTpotentialBC-pbfact1)/fact1;
                 gmaold = (model->BJTpotentialBC-pbo)/pbo;
                 here->BJTtBCcap = model->BJTdepletionCapBC/
                     (1+here->BJTtjunctionExpBC*
@@ -230,7 +238,7 @@ BJTtemp(GENmodel *inModel, CKTcircuit *ckt)
                 here->BJTtBCpot = model->BJTpotentialBC - model->BJTtvjc*dt;
             }
             if (model->BJTtlevc == 0) {
-                pbo = (model->BJTpotentialSubstrate-pbfact)/fact1;
+                pbo = (model->BJTpotentialSubstrate-pbfact1)/fact1;
                 gmaold = (model->BJTpotentialSubstrate-pbo)/pbo;
                 here->BJTtSubcap = model->BJTcapSub/
                         (1+here->BJTtjunctionExpSub*