- RFC2231 decode
- delete File*Stream
- do not output empty/illegal header on to_s
- simplify field.rb
- allow raw JIS string in quoted word
- unify character encoding of japanese strings in header
- Loader -> Mailbox
* allow this type of header: "To: Minero A. <aamine@loveruby.net>"
* write tests of Base64 module
* RFC2231 encode
* allow illegal MIME param value encoding (key="=?iso-2022-jp?B?....")
* purpose-oriented policy switching
* rewrite samples.
* address/address-group common handling scheme
* correct handling of Content-Type: message/*
* methods for mail creation, replying, forwarding
* tmail/net
* mail thread generator
