#486 Fix handling of BoundsI args if they are not per se int type

This is a pretty minor bug fix.  BoundsI had been giving errors if initialized with numpy integer types (like np.int32) rather than a regular int.  So this PR adds a fix to recast the arguments to the type that the C++ layer is expecting.  I also added a similar conversion to PositionI which had the same problem.
"BoundsI" -> "BoundsI and PositionI"