imap2_setflag_full always returns false

[tnaumann-wecg]

Checking the return result of imap2_setflag_full will always yield the value false, even if the operation was performed successfully.

I tool a quick look and saw that Message::setFlagFull is hardcoded to always return false.
Instead the result of the clients flag call should be returned.

php-imap2/src/Message.php

Lines 457 to 459 in f96973e

	$client->flag($imap->getMailboxName(), $sequence, strtoupper(substr($flag, 1)));
	return false;