update in the 3d export, and lonlat mesh construction

Geo/MPrism.h

@@ -64,6 +64,7 @@ class MPrism : public MElement {
   virtual int getNumVertices() const { return 6; }
   virtual double getInnerRadius();
   virtual MVertex *getVertex(int num){ return _v[num]; }
+  virtual void setVertex(int num,   MVertex *v){_v[num]=v;}
   virtual int getNumEdges(){ return 9; }
   virtual MEdge getEdge(int num)
   {

Geo/MTriangle.h

@@ -58,6 +58,7 @@ class MTriangle : public MElement {
   virtual double angleShapeMeasure();
   virtual int getNumVertices() const { return 3; }
   virtual MVertex *getVertex(int num){ return _v[num]; }
+  virtual void setVertex(int num,  MVertex *v){_v[num]=v;}
   virtual void xyz2uvw(double xyz[3], double uvw[3]);
   virtual MVertex *getOtherVertex(MVertex *v1, MVertex *v2)
   {