Use bare JID when checking MAM message recipient
While figuring out the recipient of a MAM message, Gajim forgets to strip the resource from the JID (or rather to assign the result of stripping the resource). In the end, Gajim won't show MAM messages that were sent to a non-bare JID of the local account. The attached patch fixes the issue.
Steps to reproduce
Use a server that supports MAM, receive a message to some non-bare JID while Gajim is offline but another resource is online, and then go online with Gajim. Gajim should now receive the message via MAM, but it won't show the message.