Implemented and documented "joiner"

--HG--
branch : trunk
diff --git a/CHANGES b/CHANGES
index c0c7139..3b50265 100644
--- a/CHANGES
+++ b/CHANGES
@@ -37,7 +37,9 @@
 - inclusions and imports "with context" forward all variables now, not only
   the initial context.
 
-- added a cycle helper called `cycle`.
+- added a cycle helper called `cycler`.
+
+- added a joining helper called `joiner`.
 
 Version 2.0
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