fixes for #722, Mechanically remove QStringRef use for QStringView to…

… help with Qt6. (#723)

* Fix typo in maggeo from search-and-replace work earlier.

* Revert startOfDate() calls to keep floor at 5.12.x to keep builders happy. :-/

* Explictly get QString from StringView in gpx for compat with older Qt builds.

Co-authored-by: Robert Lipe <robertlipe@gmail.com>

gpx.cc

@@ -894,7 +894,7 @@ void
 GpxFormat::gpx_cdata(const QStringView& s)
 {
   QString* cdata;
-  cdatastr += s;
+  cdatastr += s.toString();
 
   if (!cur_tag) {
     return;

maggeo.cc

@@ -194,7 +194,7 @@ static QDateTime maggeo_parsedate(char* dmy)
   int d = date.midRef(0,2).toInt();
   int m = date.midRef(2,2).toInt();
   int y = date.midRef(4,3).toInt();
-  QDateTime r(QDate(y + 1900, m, d)::startOfDay());
+  QDateTime r(QDate(y + 1900, m, d));
   return r;
 }
 

xcsv.cc

@@ -258,7 +258,7 @@ QDateTime
 XcsvFormat::yyyymmdd_to_time(const char* s)
 {
   QDate d = QDate::fromString(s, "yyyyMMdd");
-  return QDateTime(d.startOfDay());
+  return QDateTime(d);
 }