Shape.neighborhoodsRandomAccessible(source) doesn't require bounded source anymore.

The randomAccess(interval) on these neighborhoodsRandomAccessibles work as
expected now. That is, they extend interval by the required span and
operate on source accesses optimized for that extended interval.

Also, now HyperSphereNeighborhoodRandomAccess extends
HypersphereNeighborhoodLocalizableSampler, as it should.
Merge pull request #73 from imglib/shape-randomaccessible

Make NeighborhoodAccessibles work on potentially unbounded RandomAccessible.