Messages fetched by UID don't have $messageNum as key

[pjio]

First thanks to everyone involved in this project!

About the problem:
I'm using this library alongside with https://github.com/ddeboer/imap, which uses the UID to identify messages. In Roundcube\ImapClient::fetch() the sequence-number (variable $id) is used as the key in $result, even when $is_uid is set to true. In Javanile\Imap2\Message depending on $flags the $messageNum-parameter could either be the sequence-number or the UID. Therefore some methods fail to access the result.

What I've changed:
array_pop() is used to retrieve the message from the array and should work with sequence-numbers and UID.
If FT_UID is set, $messages will have the uid as the key in the affected functions (no change was required to Roundcube).

How I've tested it:
I fetched mails from Outlook365 via OAuth2 and by UID successfully with this change.

Possibly related:
#15
#18

[IZSkiSurfer]

Also check #32
This is a design flaw by roundcubes library. Check my ticket for how to handle it the "roundcube way"

[pjio]

@IZSkiSurfer I've changed the PR to the "Roundcube way".

This is more explicit and should have no side effects.

[IZSkiSurfer]

Thanks @pjio your fix looks fine and dandy ;)
I guess the tickets could be closed or marked as fixed with the next version.