Add Gmail IMAP extensions support

[diegovar]

Would you consider adding support for the Gmail IMAP extensions shown here?

http://code.google.com/apis/gmail/imap/

If you think you don't have enough time to implement this, could you point me in the right direction to extending node-imap to support this so I can in the future issue a pull request?

Thanks

Diego

[mscdex]

Are there specific Gmail extensions you had in mind?

[diegovar]

Mainly access to Gmail email IDs (X-GM-MSGID) and Gmail thread IDs (X-GM-THRID).

[mscdex]

I've added support for those and couple other of the extensions for Gmail with d0d078c. Let me know how it works for you.

[diegovar]

Awesome, thanks a lot! I'll test it and report any bugs I find :)

[joscha]

Just in case anyone searches for this.
Took me a dig into the source to find the right way to call search so you don't get the Incorrect number of arguments for search option: X-GM-MSGID error:

imap.search([["X-GM-MSGID", msgId]], function(err, results) {

@mscdex not sure why the double array is needed - for me it seems as if X-GM-MSGID should be on a level with SEARCH and therefore only one array needed.

[mscdex]

@joscha The reason is that there are search criteria that do not require parameters (e.g. 'UNSEEN') and you can specify these as just a single string to make things simple. So having just ["X-GM-MSGID", msgId] could be interpreted as two separate criteria or one criteria with one parameter.

[joscha]

OK, that makes total sense then, thanks for the clarification!