Unsafe numpy downcasting

[parejkoj]

If I create my mask like this, mask = (int_mask & VALUE), I get a numpy exception in PyGuide.findStars:

Cannot cast array data from dtype('uint8') to dtype('bool') according to the rule 'safe'

Doing mask = (int_mask & VALUE) != 0 will get rid of the error, but it might be good to have PyGuide either force the downcast, or just handle int mask arrays (with all 0s "good" and all non-zeros" bad).