add next-odd etc to math.bitwise

basis/math/bitwise/bitwise.factor

@@ -111,3 +111,10 @@ PRIVATE>
 : >signed ( x n -- y )
     2dup neg 1 + shift 1 = [ 2^ - ] [ drop ] if ;
 
+: >odd ( n -- int ) 0 set-bit ; foldable
+
+: >even ( n -- int ) 0 clear-bit ; foldable
+
+: next-even ( m -- n ) >even 2 + ; foldable
+
+: next-odd ( m -- n ) dup even? [ 1 + ] [ 2 + ] if ; foldable