Getting initial numpy working

Here is a simple example:
```
from numpy import empty, int32, all

def main0():
    x: i32[5] = empty(5, dtype=int32)
    x[:] = (2+3)*5
    assert all(x == 25)

main0()
```
or:
```
from numpy import empty, int32

def main0():
    x: i32[2] = empty(2, dtype=int32)
    x[0] = 3
    x[1] = 4
    assert x[0] == 3 && x[1] == 4

main0()
```