removed all isnan's and nan(NAN)'s since it was a bad idea to use them in the first place

src/include/PFitter.h

@@ -87,6 +87,7 @@ class PFitter
     bool CheckCommands();
     bool SetParameters();
 
+    bool ExecuteHesse();
     bool ExecuteMigrad();
     bool ExecuteMinimize();
     bool ExecuteMinos();

src/include/PMusr.h

@@ -234,6 +234,7 @@ typedef struct {
   PIntVector fMap;         ///<
   int fForwardHistoNo;     ///<
   int fBackwardHistoNo;    ///<
+  bool fBkgFixPresent[2];  ///< flag showing if a fixed background is present
   double fBkgFix[2];       ///<
   int fBkgRange[4];        ///<
   int fDataRange[4];       ///<