Change a lot of arguments to const references in core/gui

Rationale:
- there was a lot of large objects passed by value, so potentially
there's a speed bump from this
- even for implicitly shared classes like QString/QList there's still
a (small) cost for copying the objects when there's no reason to
- it's the right thing to do!

Author: nyalldawson

python/analysis/interpolation/qgsgridfilewriter.sip

@@ -5,7 +5,7 @@ class QgsGridFileWriter
 %End
 
   public:
-    QgsGridFileWriter( QgsInterpolator* i, QString outputPath, QgsRectangle extent, int nCols, int nRows, double cellSizeX, double cellSizeY );
+    QgsGridFileWriter( QgsInterpolator* i, const QString& outputPath, const QgsRectangle& extent, int nCols, int nRows, double cellSizeX, double cellSizeY );
     ~QgsGridFileWriter();
 
     /** Writes the grid file.

python/analysis/vector/qgspointsample.sip

@@ -7,7 +7,7 @@ class QgsPointSample
 #include <qgspointsample.h>
 %End
   public:
-    QgsPointSample( QgsVectorLayer* inputLayer, const QString& outputLayer, QString nPointsAttribute, QString minDistAttribute = QString() );
+    QgsPointSample( QgsVectorLayer* inputLayer, const QString& outputLayer, const QString& nPointsAttribute, const QString& minDistAttribute = QString() );
     ~QgsPointSample();
 
     /** Starts calculation of random points

python/analysis/vector/qgstransectsample.sip

@@ -16,9 +16,9 @@ class QgsTransectSample
       StrataUnits //units are the same as stratum layer
     };
 
-    QgsTransectSample( QgsVectorLayer* strataLayer, QString strataIdAttribute, QString minDistanceAttribute, QString nPointsAttribute,
+    QgsTransectSample( QgsVectorLayer* strataLayer, const QString& strataIdAttribute, const QString& minDistanceAttribute, const QString& nPointsAttribute,
                        DistanceUnits minDistUnits, QgsVectorLayer* baselineLayer, bool shareBaseline,
-                       QString baselineStrataId, const QString& outputPointLayer, const QString& outputLineLayer, const QString& usedBaselineLayer,
+                       const QString& baselineStrataId, const QString& outputPointLayer, const QString& outputLineLayer, const QString& usedBaselineLayer,
                        double minTransectLength = 0.0, double baselineBufferDistance = -1.0, double baselineSimplificationTolerance = -1.0 );
     ~QgsTransectSample();
 

python/analysis/vector/qgszonalstatistics.sip

@@ -31,7 +31,7 @@ class QgsZonalStatistics
     typedef QFlags<QgsZonalStatistics::Statistic> Statistics;
 
     QgsZonalStatistics( QgsVectorLayer* polygonLayer, const QString& rasterFile, const QString& attributePrefix = "", int rasterBand = 1,
-                        QgsZonalStatistics::Statistics stats = QgsZonalStatistics::Statistics( QgsZonalStatistics::Count | QgsZonalStatistics::Sum | QgsZonalStatistics::Mean) );
+                        const QgsZonalStatistics::Statistics& stats = QgsZonalStatistics::Statistics( QgsZonalStatistics::Count | QgsZonalStatistics::Sum | QgsZonalStatistics::Mean) );
     ~QgsZonalStatistics();
 
     /** Starts the calculation

python/core/auth/qgsauthcertutils.sip

@@ -46,13 +46,13 @@ class QgsAuthCertUtils
     static QString getSslProtocolName( QSsl::SslProtocol protocol );
 
 
-    static QMap< QString, QSslCertificate> mapDigestToCerts( QList<QSslCertificate> certs );
+    static QMap< QString, QSslCertificate> mapDigestToCerts( const QList<QSslCertificate>& certs );
 
 
     // static QMap< QString, QList<QSslCertificate> > certsGroupedByOrg( QList<QSslCertificate> certs );
 
 
-    static QMap< QString, QgsAuthConfigSslServer> mapDigestToSslConfigs( QList<QgsAuthConfigSslServer> configs );
+    static QMap< QString, QgsAuthConfigSslServer> mapDigestToSslConfigs( const QList<QgsAuthConfigSslServer>& configs );
 
 
     // static QMap< QString, QList<QgsAuthConfigSslServer> > sslConfigsGroupedByOrg( QList<QgsAuthConfigSslServer> configs );

python/core/auth/qgsauthconfig.sip

@@ -5,7 +5,7 @@ class QgsAuthMethodConfig
 %End
   public:
 
-    QgsAuthMethodConfig( QString method = QString(), int version = 0 );
+    QgsAuthMethodConfig( const QString& method = QString(), int version = 0 );
 
     QgsAuthMethodConfig( const QgsAuthMethodConfig& methodconfig );
 
@@ -25,7 +25,7 @@ class QgsAuthMethodConfig
     void setUri( const QString& uri );
 
     QString method() const;
-    void setMethod( QString method );
+    void setMethod( const QString& method );
 
     int version() const;
     void setVersion( int version );
@@ -36,14 +36,14 @@ class QgsAuthMethodConfig
     void loadConfigString( const QString& configstr );
 
     QgsStringMap configMap() const;
-    void setConfigMap( QgsStringMap map );
+    void setConfigMap( const QgsStringMap& map );
 
     void setConfig( const QString &key, const QString &value );
     void setConfigList( const QString &key, const QStringList &value );
 
     int removeConfig( const QString &key );
 
-    QString config( const QString &key , const QString defaultvalue = QString() ) const;
+    QString config( const QString &key, const QString& defaultvalue = QString() ) const;
 
     QStringList configList( const QString &key ) const;
 

python/core/auth/qgsauthcrypto.sip

@@ -7,9 +7,9 @@ class QgsAuthCrypto
   public:
     static bool isDisabled();
 
-    static const QString encrypt( QString pass, QString cipheriv, QString text );
+    static const QString encrypt( const QString& pass, const QString& cipheriv, const QString& text );
 
-    static const QString decrypt( QString pass, QString cipheriv, QString text );
+    static const QString decrypt( const QString& pass, const QString& cipheriv, const QString& text );
 
     static void passwordKeyHash( const QString &pass,
                                  QString *salt,

python/core/auth/qgsauthmanager.sip

@@ -24,7 +24,7 @@ class QgsAuthManager : QObject
 
     const QString authDbServersTable() const;
 
-    bool init( QString pluginPath = QString::null );
+    bool init( const QString& pluginPath = QString::null );
 
     bool isDisabled() const;
 
@@ -107,9 +107,9 @@ class QgsAuthManager : QObject
 
     ////////////////// Generic settings ///////////////////////
 
-    bool storeAuthSetting( const QString& key, QVariant value, bool encrypt = false );
+    bool storeAuthSetting( const QString& key, const QVariant& value, bool encrypt = false );
 
-    QVariant getAuthSetting( const QString& key, QVariant defaultValue = QVariant(), bool decrypt = false );
+    QVariant getAuthSetting( const QString& key, const QVariant& defaultValue = QVariant(), bool decrypt = false );
 
     bool existsAuthSetting( const QString& key );
 

python/core/auth/qgsauthmethod.sip

@@ -50,8 +50,8 @@ class QgsAuthMethod : QObject
 
     void setVersion( int version );
 
-    void setExpansions( QgsAuthMethod::Expansions expansions );
-    void setDataProviders( QStringList dataproviders );
+    void setExpansions( const QgsAuthMethod::Expansions& expansions );
+    void setDataProviders( const QStringList& dataproviders );
 };
 
 typedef QHash<QString, QgsAuthMethod*> QgsAuthMethodsMap;

python/core/composer/qgsatlascomposition.sip

@@ -137,7 +137,7 @@ public:
     QString featureFilterErrorString() const;
 
     QString sortKeyAttributeName() const;
-    void setSortKeyAttributeName( QString fieldName );
+    void setSortKeyAttributeName( const QString& fieldName );
 
     /** Returns the current list of predefined scales for the atlas. This is used
      * for maps which are set to the predefined atlas scaling mode.