grab retention time from msgf+ mzidentml files

src/input/identificationpwizreader.cpp

@@ -478,8 +478,14 @@ IdentificationPwizReader::read(
                 {
                   // throw pappso::PappsoException(QObject::tr("Scan number not
                   // found"));
+                  //<cvParam cvRef="PSI-MS" accession="MS:1000016" name="scan
+                  //start time" value="4075.63" unitAccession="UO:0000010"
+                  //unitName="second" unitCvRef="UO"/>
+                  rt = getQVariantDoubleParam(spectrum_ptr.get(),
+                                              pwiz::cv::MS_scan_start_time);
                 }
 
+
               //<SpectrumIdentificationItem passThreshold="true" rank="1"
               // experimentalMassToCharge="388.2189331" id="sii2"
               // chargeState="2" calculatedMassToCharge="388.2161235">