Precursor logic streamlined

The same precursor selection logic as for other file formats
TBD: Move some of the service functions to the SpectrumWriter base class

Author: caetera

Writer/MzMlSpectrumWriter.cs

@@ -1286,7 +1286,7 @@ private SpectrumType ConstructMSSpectrum(int scanNumber)
             int? charge = trailerData.AsPositiveInt("Charge State:");
             double? monoisotopicMz = trailerData.AsDouble("Monoisotopic M/Z:");
             double? ionInjectionTime = trailerData.AsDouble("Ion Injection Time (ms):");
-            double? isolationWidth = trailerData.AsDouble("MS" + (int) scanFilter.MSOrder + " Isolation Width:");
+            double? isolationWidth = trailerData.AsDouble("MS" + msLevel + " Isolation Width:");
             double? FAIMSCV = null;
             if (trailerData.AsBool("FAIMS Voltage On:").GetValueOrDefault(false))
                 FAIMSCV = trailerData.AsDouble("FAIMS CV:");