Overflow and segmentation fault

[hgeorgsch]

On nyquist we get segmentation fault on the very first simulation. (regressiontest.sh) On shannon, the same code gives an overflow warning and subsequent error exception trying to convert NaN to to int; this happens on the first point mass image.

[hgeorgsch]

The overflow happens in centreImage()

[hgeorgsch]

The cause seems to be the new code to transfer floating point cv::Mat to python. See #102

[hgeorgsch]

The problem was the wrong bitwise operation, changing OR to AND solved the problem.