V0.1 of tests get_active_hardlocations(bitstring)

This draft codebase scans 2**20 hard locations (of 256 bits), and
computes the hamming distance from the bitstring.

I’m working on retrieving *exactly* the indexes and distances of these
locations, using either pyopencl.scan.GenericScanKernel().  Pretty
tough so far with close to zero documentation…