Doxygenation and small code fixes

Author: m-kuhn

src/core/qgsvectorlayer.cpp

@@ -2801,7 +2801,7 @@ void QgsVectorLayer::removeExpressionField( int index )
   emit attributeDeleted( index );
 }
 
-const QString QgsVectorLayer::expressionField( int index )
+QString QgsVectorLayer::expressionField( int index )
 {
   int oi = mUpdatedFields.fieldOriginIndex( index );
   return mExpressionFieldBuffer->expressions().value( oi ).expression;

src/core/qgsvectorlayer.h

@@ -595,7 +595,7 @@ class CORE_EXPORT QgsVectorLayer : public QgsMapLayer
      *
      * @note added in 2.9
      */
-    const QString expressionField( int index );
+    QString expressionField( int index );
 
     /**
      * Changes the expression used to define an expression based (virtual) field
@@ -608,9 +608,10 @@ class CORE_EXPORT QgsVectorLayer : public QgsMapLayer
      */
     void updateExpressionField( int index, const QString& exp );
 
-    /** Get the label object associated with this layer */
+    /** Get the label rendering properties associated with this layer */
     QgsLabel *label();
 
+    /** Get the label rendering properties associated with this layer */
     const QgsLabel *label() const;
 
     QgsAttributeAction *actions() { return mActions; }