Merge pull request #5 from javierz/master

Mail fixes + more
*fixed mails not being able to be seen in mailbox when they were sent to you whilst you were logged in.
*supports sending items in the mail
*fixed a bug which would cause bugs when moving items around in your inventory
*fixed items not appearing in mail if it had more than 8
+Groups support! You can now invite players into your group and play with them!
*renamed MailHandler.cs -> MailHandlers.cs
*groups can no longer contain the same player twice.
*shows message to all people that a new player has joined.
*player stats now appear properly. Not sure how armor is sent yet.