Concatenate yields unexpected results

[Yvee1]

Observed behaviour

Example:

fun main() {
    val A1 = mk.identity<Double>(3)
    println("A1")
    println(A1)
    val A2 = mk.ones<Double>(3, 1)
    println("A2")
    println(A2)
    println("A1 A2")
    println(A1.cat(A2, axis=1))
}

gives

A1
[[1.0, 0.0, 0.0],
[0.0, 1.0, 0.0],
[0.0, 0.0, 1.0]]
A2
[[0.0],
[0.0],
[0.0]]
A1 A2
[[1.0, 0.0, 0.0, 0.0, 0.0, 0.0],
[0.0, 0.0, 0.0, 0.0, 0.0, 0.0],
[0.0, 0.0, 0.0, 0.0, 0.0, 0.0]]

Expected results

Comparison with numpy:

A1 = np.identity(3)
A2 = np.ones((3, 1))
np.concatenate((A1, A2), axis=1)

gives

array([[1., 0., 0., 1.],
       [0., 1., 0., 1.],
       [0., 0., 1., 1.]])

[devcrocod]

fixes #72