[bug-mailutils] How could I get the info using ENVELOPE cmd?

[Sung-jar Park]

Hello,
I'm currently writing email client tool using libmailutils 2.1.2
For the IMAP protocol.

But in my case sometimes the sender did not send a well formatted email 
message. Some fields of message are not encoded in rfc2047.

Especially subject and from and to fields.

So i try to solve this problem and i got the answers.

The imap server send the correctly encoded subject and what I needs when i send 
the fetch envelope command.

So i starting to find the api of libmailutils to retrive the result of the 
fetch envelope command.

But i found a comment that the mailutils does not supporting the fetch envelop 
command.

So i wrote this.

Do you have any fututre plan to support this command?

About fetching the subject via envelope command.