Checking in changes prior to tagging of version 0.2.1.

Changelog diff is:

diff --git a/History.md b/History.md
index 74e502f..05ed56b 100644
--- a/History.md
+++ b/History.md
@@ -1,3 +1,8 @@
+0.2.1 / 2013-04-04
+==================
+
+  * Improved portability(Support big endian enviromet)
+
 0.2.0 / 2013-03-18
 ==================