Forget to put a reference in the return of the method in the interface particle

(but this interface is currently unused)

git-svn-id: svn+ssh://scm.gforge.inria.fr/svn/scalfmm/scalfmm/trunk@137 2616d619-271b-44dc-8df4-d4a8f33a7222

Src/Components/FAbstractParticle.hpp

@@ -32,7 +32,7 @@ public:
 	* Must be implemented by each user Particle class
 	* @return the position of the current cell
 	*/
-	virtual F3DPosition getPosition() const = 0;
+        virtual const F3DPosition& getPosition() const = 0;
 };