Use proper unicode collation for sorting strings, and make the w/collation-key public

basis/sorting/human/human.factor

@@ -2,7 +2,7 @@
 ! See http://factorcode.org/license.txt for BSD license.
 USING: accessors fry kernel make math math.order math.parser
 sequences sorting.functor strings unicode.case
-unicode.categories ;
+unicode.categories unicode.collation ;
 IN: sorting.human
 
 : cut-find ( seq pred -- before after )
@@ -33,7 +33,7 @@ TUPLE: hybrid obj ;
 
 : <hybrid-insensitive> ( obj -- hybrid )
     hybrid new
-        swap dup string? [ >case-fold ] when >>obj ; inline
+        swap dup string? [ w/collation-key ] when >>obj ; inline
 
 M: hybrid <=>
     [ obj>> ] bi@

basis/unicode/collation/collation.factor

@@ -149,10 +149,8 @@ PRIVATE>
 : quaternary= ( str1 str2 -- ? )
     0 insensitive= ;
 
-<PRIVATE
 : w/collation-key ( str -- {str,key} )
     [ collation-key ] keep 2array ;
-PRIVATE>
 
 : sort-strings ( strings -- sorted )
     [ w/collation-key ] map natural-sort values ;