add N0 estimate to single histogram fit. Some improvements in musredit (see ChangLog)

src/include/PMusr.h

@@ -738,4 +738,14 @@ typedef struct {
   UInt_t idf;                ///< IDF version for NeXus files.
 } PAny2ManyInfo;
 
+//-------------------------------------------------------------
+/**
+ * <p>Holds the informations for the any2many converter program
+ */
+typedef struct {
+  Bool_t writeExpectedChisq; ///< if set to true, expected chisq per block will be written
+  Bool_t estimateN0;         ///< if set to true, for single histogram fits N0 will be estimated
+  Double_t alphaEstimateN0;  ///< relates the Bkg to N0, i.e. Bkg = alpha*N0
+} PStartupOptions;
+
 #endif // _PMUSR_H_