Remove old util-kwargs, replace with Racket-compatible define*/lambda* forms.

doc/utils.md

@@ -229,20 +229,6 @@ Executes given command ```cmd``` with given argument list ```args```
 writing all ```lines``` to its standard input and then reads all the
 process output.
 
-### Keyword Arguments
-
-    (import util-kwargs)
-
-A simple module providing convenient syntax for defining procedures
-with keyword arguments with default values.
-
-    (define-kwproc (name arg ... (#:kw binding [default]) ...) body ...)
-
-Defines new procedure ```name``` with positional arguments ```arg
-...``` and optional keyword arguments with implicit default value
-```#f``` or any specific value given in the keyword argument
-specification.
-
 ### List
 
     (import util-list)