Rename CroppedIterableInterval to HyperSlice

HyperSlice is a better name, as the underlying algorithm doesn't actually
crop the data, but simply creating 'HyperSlice' views on it.
Slicewise: Update JavaDoc
SlicewiseUtils: Added Util class to get indices from axes
Using Slicewise.NAME instead of fixed "slicemapper"
SlicewiseRAI2RAI: Formatting