ts_sort_prefixed_numeric had an unusal meaning in that it sorted by any
trailing digits in a word, thus for example, sorting by the name column
in the reserved node list would get you stuff like:
	pc2 pc3 ixp4 pc5 pcwf6 pc8 plab9 pc10 ...
This didn't seem terribly intuitive.  Perhaps there was a specific context
where this makes sense, but I haven't found it!  So now it sorts first by
leading non-numeric value and then by numeric suffix.