Altered filesizeformat to support both MB and MiB, documented `{% filter %}`.

--HG--
branch : trunk
diff --git a/CHANGES b/CHANGES
index 03a125c..f27f5f4 100644
--- a/CHANGES
+++ b/CHANGES
@@ -27,6 +27,9 @@
 
 - improved error reporting for undefined values by providing a position.
 
+- `filesizeformat` filter uses decimal prefixes now per default and can be
+  set to binary mode with the second parameter.
+
 Version 2.0rc1
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 (no codename, released on June 9th 2008)