Mention 3.0.1 in the changelog, bump the next version to 3.1.0.

Closes #2211.

doc/CHANGES.txt

@@ -1,4 +1,4 @@
-2013-??-??: 3.0.1
+2013-??-??: 3.1.0
 	all : allowed null-patterns in pattern matching
 	all : optimized pattern matching output
 	all : added length field to BytesBuffer, BytesOutput, BytesInput and StringBuf
@@ -18,6 +18,9 @@
 	macro : resolve error line number in external files
 	flash : fixed font embedding with UTF8 chars
 
+2013-09-25: 3.0.1
+	all : minor DCE bug fix
+
 2013-05-25: 3.0.0
 	all : added haxe.ds.BalancedTree
 	all : added haxe.ds.EnumValueMap