update HISTORY.TXT for major 7.0 features

Author: tbonfort

HISTORY.TXT

@@ -12,7 +12,16 @@ the top of the list.)
 
 For a complete change history, please see the Git log comments.
 
-6.4 release (2013/09/xx)
+7.0 release (TBD)
+-----------------
+
+- RFC103 Layer Level Character Encoding
+
+- RFC99 GD removal
+
+- RFC98 Complex Text Rendering / Text Rendering Overhaul
+
+6.4 release (2013/09/17)
 ---------------------------
 
 - RFC 101: Support for Content Dependant Legend Rendering