Made value, pointer and reference type const in order to comply with boost...

Made value, pointer and reference type const in order to comply with boost range specifications. Thanks to Vladimir Chalupecky for this hint.

git-svn-id: http://www.openvolumemesh.org/svnrepo/OpenVolumeMesh/trunk@287 66977474-1d4b-4f09-8fe9-267525286df2

src/OpenVolumeMesh/Core/Iterators.hh

@@ -61,7 +61,7 @@ public:
 	// STL compliance
 	typedef std::bidirectional_iterator_tag iterator_category;
 	typedef int						        difference_type;
-	typedef OH  					        value_type;
+	typedef const OH				        value_type;
 	typedef const OH*				        pointer;
 	typedef const OH&				        reference;