Macro reshape

macro_rules! reshape {
    (
        ty $ty:ty,
        n $n:expr,
        shape $shape:expr,
        array $array:expr
    ) => { ... };
    (
        ty $ty:ty,
        shape $shape:expr,
        array $array:expr,
        d $D:expr
    ) => { ... };
}

Reshapes an array into a tensor.