C++11: Got rid of narrowing conversion warnings in legacy code.

Added explicit static_cast along with static SFINAE checks to VectorT
constructor.

src/OpenMesh/Core/Geometry/VectorT.hh

@@ -92,6 +92,23 @@ namespace OpenMesh {
 //== CLASS DEFINITION =========================================================
 
 
+#if CPP11_ENABLED
+/*
+ * Helpers for VectorT
+ */
+namespace {
+template<typename... Ts>
+struct are_convertible_to;
+
+template<typename To, typename From, typename... Froms>
+struct are_convertible_to<To, From, Froms...> {
+    static constexpr bool value = std::is_convertible<From, To>::value && are_convertible_to<To, Froms...>::value;
+};
+template<typename To, typename From>
+struct are_convertible_to<To, From> : public std::is_convertible<From, To> {};
+}
+#endif
+
 
 /** The N values of the template Scalar type are the only data members
     of the class VectorT<Scalar,N>. This guarantees 100% compatibility

src/OpenMesh/Core/Geometry/VectorT_inc.hh

@@ -102,8 +102,10 @@ public:
       vectorize(v);
   }
 
-  template<typename... T, typename = typename std::enable_if<sizeof...(T) == DIM>::type>
-  constexpr VectorT(T... vs) : Base {vs...}
+  template<typename... T,
+      typename = typename std::enable_if<sizeof...(T) == DIM>::type,
+      typename = typename std::enable_if<are_convertible_to<float, T...>::value>::type>
+  constexpr VectorT(T... vs) : Base { static_cast<Scalar>(vs)...}
   { }
 #else
   /// special constructor for 1D vectors