io.streams.random: adding @erg's random-stream.

extra/io/streams/random/authors.txt

@@ -0,0 +1 @@
+Doug Coleman

extra/io/streams/random/random.factor

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+! Copyright (C) 2010 Doug Coleman.
+! See http://factorcode.org/license.txt for BSD license.
+USING: destructors io kernel random sequences ;
+IN: io.streams.random
+
+TUPLE: random-stream ;
+
+C: <random-stream> random-stream
+
+M: random-stream stream-element-type drop +byte+ ;
+
+M: random-stream stream-read-unsafe
+    drop [ dup random-bytes ] [ 0 swap copy ] bi* ;
+
+M: random-stream stream-read1 drop 256 random ;
+
+M: random-stream stream-read-partial-unsafe stream-read-unsafe ;
+
+M: random-stream dispose drop ;
+
+INSTANCE: random-stream input-stream