Deprecated numpy types

As of numpy 1.20 `np.float` and `np.int` are deprecated; in the past they were just aliases.

So those should be removed from the code (main code + tests)

via (e.g.):
```sh
grep -rl 'np.int' . | xargs sed -i 's/np.int/int/g'
grep -rl 'np.float' . | xargs sed -i 's/np.float/float/g'
```