+ Optimize recursive decoding.
+
+ Fix a bug - decode message/rfc822 subparts.
+
+WHAT'S NEW in version 2.3.3 (2014-02-02)
+ Forbid filtering from console. When the program runs with stdin
+ connected to the console it shows usage help.
+
+ Fix a bug - option -o and no parameters.
+
+WHAT'S NEW in version 2.3.2 (2014-02-01)
+ Fix a bug - do not generate 'From ' headers in subparts.
+
+ Add option --host.
+
+ Add tests.
+
+WHAT'S NEW in version 2.3.1 (2014-01-31)
+ Update documentation.
+
+WHAT'S NEW in version 2.3.0 (2014-01-30)
+ Add option -o and output_file argument.