Added missing tensor copy constructors. As a result it is now possible to declare and initialize a tensor on the same line, as in:   Tensor<bla> T = A + B;  or   Tensor<bla> T(A.reshape(new_shape));
Added missing tensor copy constructors. As a result it is now possible to declare and initialize a tensor on the same line, as in:
  Tensor<bla> T = A + B;  or
  Tensor<bla> T(A.reshape(new_shape));

madlib/eigen,madlib/eigen,madlib/eigen,madlib/eigen