Add support for Slice to Matrix, SquareMatrix, Vector

matrix/Vector2.hpp

@@ -43,6 +43,11 @@ public:
         v(1) = y;
     }
 
+    template<size_t P, size_t Q>
+    Vector2(const Slice<Type, 2, 1, P, Q>& slice_in) : Vector<Type, 2>(slice_in)
+    {
+    }
+
     explicit Vector2(const Vector3 & other)
     {
         Vector2 &v(*this);