[netinstall] Rip out derpy translations of PackageModel

- The model always has two columns, and the column names are always
  the same. We don't need to specially set headers for that.
- Use QCoreApplication::translation() to re-use the existing
  translations and avoid creating "new" strings (in a new context).

src/modules/netinstall/NetInstallPage.cpp

@@ -66,15 +66,9 @@ NetInstallPage::setPageTitle( CalamaresUtils::Locale::TranslatedString* t )
     retranslate();
 }
 
-
 void
 NetInstallPage::retranslate()
 {
-    if ( m_groups )
-    {
-        m_groups->setHeaderData( 0, Qt::Horizontal, tr( "Name" ) );
-        m_groups->setHeaderData( 1, Qt::Horizontal, tr( "Description" ) );
-    }
     if ( ui && m_title )
     {
         ui->label->setText( m_title->get() );  // That's get() on the TranslatedString

src/modules/netinstall/PackageModel.cpp

@@ -21,9 +21,11 @@
 
 #include "utils/Yaml.h"
 
+// TODO: see headerData(), remove after 3.2.19
+#include <QCoreApplication>
+
 PackageModel::PackageModel( const YAML::Node& data, QObject* parent )
     : QAbstractItemModel( parent )
-    , m_columnHeadings()
 {
     m_rootItem = new PackageTreeItem();
     setupModelData( data, m_rootItem );
@@ -150,26 +152,6 @@ PackageModel::setData( const QModelIndex& index, const QVariant& value, int role
     return true;
 }
 
-bool
-PackageModel::setHeaderData( int section, Qt::Orientation orientation, const QVariant& value, int role )
-{
-    Q_UNUSED( role )
-
-    if ( orientation == Qt::Horizontal )
-    {
-        if ( m_columnHeadings.value( section ) != QVariant() )
-        {
-            m_columnHeadings.replace( section, value );
-        }
-        else
-        {
-            m_columnHeadings.insert( section, value );
-        }
-        emit headerDataChanged( orientation, section, section );
-    }
-    return true;
-}
-
 Qt::ItemFlags
 PackageModel::flags( const QModelIndex& index ) const
 {
@@ -189,7 +171,12 @@ PackageModel::headerData( int section, Qt::Orientation orientation, int role ) c
 {
     if ( orientation == Qt::Horizontal && role == Qt::DisplayRole )
     {
-        return m_columnHeadings.value( section );
+        // Unusual translation call uses the existing translation from the NetInstallPage
+        // class (now removed).
+        //
+        // TODO: after 3.2.19, change this to just tr() and push TX
+        return ( section == 0 ) ? QCoreApplication::translate( "NetInstallPage", "Name" )
+                                : QCoreApplication::translate( "NetInstallPage", "Description" );
     }
     return QVariant();
 }

src/modules/netinstall/PackageModel.h

@@ -44,14 +44,15 @@ public:
 
     QVariant data( const QModelIndex& index, int role ) const override;
     bool setData( const QModelIndex& index, const QVariant& value, int role = Qt::EditRole ) override;
-    bool
-    setHeaderData( int section, Qt::Orientation orientation, const QVariant& value, int role = Qt::EditRole ) override;
     Qt::ItemFlags flags( const QModelIndex& index ) const override;
-    QVariant headerData( int section, Qt::Orientation orientation, int role = Qt::DisplayRole ) const override;
+
     QModelIndex index( int row, int column, const QModelIndex& parent = QModelIndex() ) const override;
     QModelIndex parent( const QModelIndex& index ) const override;
+
+    QVariant headerData( int section, Qt::Orientation orientation, int role = Qt::DisplayRole ) const override;
     int rowCount( const QModelIndex& parent = QModelIndex() ) const override;
     int columnCount( const QModelIndex& parent = QModelIndex() ) const override;
+
     PackageItemDataList getPackages() const;
     QList< PackageTreeItem* > getItemPackages( PackageTreeItem* item ) const;
 
@@ -60,7 +61,6 @@ private:
 
     PackageTreeItem* m_rootItem;
     QList< PackageTreeItem* > m_hiddenItems;
-    QVariantList m_columnHeadings;
 };
 
 #endif  // PACKAGEMODEL_H