Fixing translation of the ones, zeros, and inf functions

There are a few special cases, which get handled correctly now:
```matlab
function test()
 a = ones(4);
 b = zeros(4,3);
 c = inf('single');
 d = ones(4,2,'double');
```

```python
def test():
    a = np.ones(shape=(4, 4), dtype='float64')
    b = np.zeros(shape=(4, 3), dtype='float64')
    c = (np.zeros(shape=(), dtype='single') + np.inf)
    d = np.ones(shape=(4, 2), dtype='double')
    return
```

The calls are a bit more verbose now. This could be remedied to some extent, but it would make the backend code more complex.