Remove superfluous QScopedPointer<>s in singletons

There was a curious pattern of singletons being implemented based on
QScopedPointer<>s. This is an unnecessary level of indirection:
The lifetime of the smart pointer is the same as that of the
pointed-to object. Therefore, replace these pointers by the respective
objects.

Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>

core/gettextfromc.cpp

@@ -18,8 +18,8 @@ void gettextFromC::reset(void)
 
 gettextFromC *gettextFromC::instance()
 {
-	static QScopedPointer<gettextFromC> self(new gettextFromC());
-	return self.data();
+	static gettextFromC self;
+	return &self;
 }
 
 extern "C" const char *trGettext(const char *text)

qt-models/cylindermodel.cpp

@@ -31,8 +31,8 @@ QVariant CylindersModel::headerData(int section, Qt::Orientation orientation, in
 CylindersModel *CylindersModel::instance()
 {
 
-	static QScopedPointer<CylindersModel> self(new CylindersModel());
-	return self.data();
+	static CylindersModel self;
+	return &self;
 }
 
 static QString get_cylinder_string(cylinder_t *cyl)

qt-models/diveplannermodel.cpp

@@ -412,8 +412,8 @@ DivePlannerPointsModel::DivePlannerPointsModel(QObject *parent) : QAbstractTable
 
 DivePlannerPointsModel *DivePlannerPointsModel::instance()
 {
-	static QScopedPointer<DivePlannerPointsModel> self(new DivePlannerPointsModel());
-	return self.data();
+	static DivePlannerPointsModel self;
+	return &self;
 }
 
 void DivePlannerPointsModel::emitDataChanged()

qt-models/models.cpp

@@ -32,8 +32,8 @@ Qt::ItemFlags GasSelectionModel::flags(const QModelIndex &index) const
 
 GasSelectionModel *GasSelectionModel::instance()
 {
-	static QScopedPointer<GasSelectionModel> self(new GasSelectionModel());
-	return self.data();
+	static GasSelectionModel self;
+	return &self;
 }
 
 //TODO: Remove this #include here when the issue below is fixed.

qt-models/tankinfomodel.cpp

@@ -6,8 +6,8 @@
 
 TankInfoModel *TankInfoModel::instance()
 {
-	static QScopedPointer<TankInfoModel> self(new TankInfoModel());
-	return self.data();
+	static TankInfoModel self;
+	return &self;
 }
 
 const QString &TankInfoModel::biggerString() const

qt-models/weigthsysteminfomodel.cpp

@@ -6,8 +6,8 @@
 
 WSInfoModel *WSInfoModel::instance()
 {
-	static QScopedPointer<WSInfoModel> self(new WSInfoModel());
-	return self.data();
+	static WSInfoModel self;
+	return &self;
 }
 
 bool WSInfoModel::insertRows(int row, int count, const QModelIndex &parent)