Correct German variable names translation in Calc (financial)

This aligns the translation of the "Zins" argument of the financial
functions to "Rate", as used in the function documentation in English.
The original translation was done by the same author recently in
the commit 8ba9dfe2.

Compare (as in MS Excel):
German: https://help.libreoffice.org/Calc/Financial_Functions_Part_Two/de#RMZ
English: https://help.libreoffice.org/Calc/Financial_Functions_Part_Two#PMT

Change-Id: Ifa125d94a639c91c454d7b540f86feeecea250ff
Reviewed-on: https://gerrit.libreoffice.org/44021Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Eike Rathke <erack@redhat.com>

scaddins/source/analysis/analysishelper.cxx

@@ -1231,36 +1231,36 @@ double GetOddlyield( sal_Int32 nNullDate, sal_Int32 nSettle, sal_Int32 nMat, sal
 }
 
 
-double GetRmz( double fInterest, double fNper, double fPv, double fFv, sal_Int32 nPayType )
+double GetRmz( double fRate, double fNper, double fPv, double fFv, sal_Int32 nPayType )
 {
     double      fPmt;
-    if( fInterest == 0.0 )
+    if( fRate == 0.0 )
         fPmt = ( fPv + fFv ) / fNper;
     else
     {
-        double  fTerm = pow( 1.0 + fInterest, fNper );
+        double  fTerm = pow( 1.0 + fRate, fNper );
         if( nPayType > 0 )
-            fPmt = ( fFv * fInterest / ( fTerm - 1.0 ) + fPv * fInterest / ( 1.0 - 1.0 / fTerm ) ) / ( 1.0 + fInterest );
+            fPmt = ( fFv * fRate / ( fTerm - 1.0 ) + fPv * fRate / ( 1.0 - 1.0 / fTerm ) ) / ( 1.0 + fRate );
         else
-            fPmt = fFv * fInterest / ( fTerm - 1.0 ) + fPv * fInterest / ( 1.0 - 1.0 / fTerm );
+            fPmt = fFv * fRate / ( fTerm - 1.0 ) + fPv * fRate / ( 1.0 - 1.0 / fTerm );
     }
 
     return -fPmt;
 }
 
 
-double GetZw( double fInterest, double fNper, double fPmt, double fPv, sal_Int32 nPayType )
+double GetZw( double fRate, double fNper, double fPmt, double fPv, sal_Int32 nPayType )
 {
     double      fFv;
-    if( fInterest == 0.0 )
+    if( fRate == 0.0 )
         fFv = fPv + fPmt * fNper;
     else
     {
-        double  fTerm = pow( 1.0 + fInterest, fNper );
+        double  fTerm = pow( 1.0 + fRate, fNper );
         if( nPayType > 0 )
-            fFv = fPv * fTerm + fPmt * ( 1.0 + fInterest ) * ( fTerm - 1.0 ) / fInterest;
+            fFv = fPv * fTerm + fPmt * ( 1.0 + fRate ) * ( fTerm - 1.0 ) / fRate;
         else
-            fFv = fPv * fTerm + fPmt * ( fTerm - 1.0 ) / fInterest;
+            fFv = fPv * fTerm + fPmt * ( fTerm - 1.0 ) / fRate;
     }
 
     return -fFv;

scaddins/source/analysis/analysishelper.hxx

@@ -155,8 +155,8 @@ double              GetOddlprice( sal_Int32 nNullDate, sal_Int32 nSettle, sal_In
 /// @throws css::lang::IllegalArgumentException
 double              GetOddlyield( sal_Int32 nNullDate, sal_Int32 nSettle, sal_Int32 nMat, sal_Int32 nLastInterest,
                                 double fRate, double fPrice, double fRedemp, sal_Int32 nFreq, sal_Int32 nBase );
-double              GetRmz( double fInterest, double fNper, double fPv, double fFv, sal_Int32 nPayType );
-double              GetZw( double fInterest, double fNper, double fPmt, double fPv, sal_Int32 nPayType );
+double              GetRmz( double fRate, double fNper, double fPv, double fFv, sal_Int32 nPayType );
+double              GetZw( double fRate, double fNper, double fPmt, double fPv, sal_Int32 nPayType );
 
 /// @throws css::uno::RuntimeException
 /// @throws css::lang::IllegalArgumentException