[welcome] Don't const& POD

- simplify parameter types in some set-methods
- while here, shuffle methods to bring things together

src/modules/welcome/Config.cpp

@@ -159,7 +159,7 @@ Config::setLanguageIcon( const QString& languageIcon )
 }
 
 void
-Config::setLocaleIndex( const int& index )
+Config::setLocaleIndex( int index )
 {
     if ( index == m_localeIndex || index > CalamaresUtils::Locale::availableTranslations()->rowCount( QModelIndex() )
          || index < 0 )
@@ -170,7 +170,7 @@ Config::setLocaleIndex( const int& index )
     m_localeIndex = index;
 
     const auto& selectedLocale = m_languages->locale( m_localeIndex ).locale();
-    cDebug() << "Selected locale" << selectedLocale;
+    cDebug() << "Index" << index << "Selected locale" << selectedLocale;
 
     QLocale::setDefault( selectedLocale );
     CalamaresUtils::installTranslator( selectedLocale, Calamares::Branding::instance()->translationsDirectory() );
@@ -185,7 +185,7 @@ Config::requirementsModel() const
 }
 
 void
-Config::setIsNextEnabled( const bool& isNextEnabled )
+Config::setIsNextEnabled( bool isNextEnabled )
 {
     m_isNextEnabled = isNextEnabled;
     emit isNextEnabledChanged( m_isNextEnabled );

src/modules/welcome/Config.h

@@ -49,13 +49,17 @@ class Config : public QObject
 
 public:
     Config( QObject* parent = nullptr );
+
+    Calamares::RequirementsModel& requirementsModel() const;
+
     void setCountryCode( const QString& countryCode );
+
+    QString languageIcon() const;
     void setLanguageIcon( const QString& languageIcon );
-    Calamares::RequirementsModel& requirementsModel() const;
 
-    void setIsNextEnabled( const bool& isNextEnabled );
+    void setIsNextEnabled( bool isNextEnabled );
 
-    void setLocaleIndex( const int& index );
+    void setLocaleIndex( int index );
     int localeIndex() const { return m_localeIndex; }
 
     QString supportUrl() const;
@@ -76,7 +80,6 @@ public:
 public slots:
     CalamaresUtils::Locale::LabelModel* languagesModel() const;
     void retranslate();
-    QString languageIcon() const;
 
 signals:
     void countryCodeChanged( QString countryCode );