Add functionality to switch mailbox(es) without opening a new connection

[pixelpeter]

Currently it's not possible to search multiple folders without re-connecting to the server.
This PR can solve this issue
Just added this simple function to Mailbox.php

    public function switchMailbox($imapPath = '') {
        $this->imapPath = $imapPath;
        $imapStream = @imap_reopen($this->getImapStream(), $imapPath);
        if(!$imapStream) {
            throw new Exception("Couldn't switch  mailbox: " . imap_last_error());
        }
    }

Now you can do this:

// Connect to INBOX on server and search for mails
$mailbox = new PhpImap\Mailbox('{imap.example.org.com:993/imap/ssl}INBOX', '[email protected]', '*********', __DIR__);
$mailIds = $mailbox->searchMailbox('ALL');

// store all mails in $inbox
$inbox = [];
foreach($mailIds as $mailId)
{
    $inbox[] = $mailbox->getMail($mailId, false);
}

// Switch to other folder without opening new connection
$mailbox->switchMailbox('{imap.example.org.com:993/imap/ssl}INBOX.Sent');
$mailIds = $mailbox->searchMailbox('ALL');

// store all mails in $sent
$sent = [];
foreach($mailIds as $mailId)
{
    $sent[] = $mailbox->getMail($mailId, false);
}

HINT: It's important to fetch the actual mails BEFORE switching to another mailbox.

Hope you'll find this useful.

[melino]

Fantastic, exactly what I have just missed. Thx!

[underdpt]

Shouldn't this patch set the class variable $imapStream? At the end of the function:

$this->imapStream = $imapStream;

[decadence]

#187