Remove unimplemented QgsSurfaceV2::pointOnSurface method

Was always returning a point not on the surface! (0,0). Use the
GEOS method instead.

Author: nyalldawson

python/core/geometry/qgscurvepolygonv2.sip

@@ -30,7 +30,6 @@ class QgsCurvePolygonV2: public QgsSurfaceV2
     //surface interface
     virtual double area() const;
     virtual double perimeter() const;
-    QgsPointV2 pointOnSurface() const;
     QgsPolygonV2* surfaceToPolygon() const;
 
     //curve polygon interface

python/core/geometry/qgssurfacev2.sip

@@ -5,6 +5,5 @@ class QgsSurfaceV2: public QgsAbstractGeometryV2
 %End
 
   public:
-    virtual QgsPointV2 pointOnSurface() const = 0;
     virtual QgsPolygonV2* surfaceToPolygon() const = 0;
 };

src/core/geometry/qgscurvepolygonv2.cpp

@@ -399,11 +399,6 @@ double QgsCurvePolygonV2::perimeter() const
   return perimeter;
 }
 
-QgsPointV2 QgsCurvePolygonV2::pointOnSurface() const
-{
-  return QgsPointV2( 0, 0 );
-}
-
 QgsPolygonV2* QgsCurvePolygonV2::surfaceToPolygon() const
 {
   QgsPolygonV2* polygon = new QgsPolygonV2();

src/core/geometry/qgscurvepolygonv2.h

@@ -56,7 +56,6 @@ class CORE_EXPORT QgsCurvePolygonV2: public QgsSurfaceV2
     //surface interface
     virtual double area() const override;
     virtual double perimeter() const override;
-    QgsPointV2 pointOnSurface() const override;
     QgsPolygonV2* surfaceToPolygon() const override;
 
     //curve polygon interface

src/core/geometry/qgssurfacev2.h

@@ -26,7 +26,7 @@ class QgsPolygonV2;
 class CORE_EXPORT QgsSurfaceV2: public QgsAbstractGeometryV2
 {
   public:
-    virtual QgsPointV2 pointOnSurface() const = 0;
+
     virtual QgsPolygonV2* surfaceToPolygon() const = 0;
 };