MailMover : Use folder replacement and regex in settings.

This patch allows to match folder by regex in the mailmover rules and to replace the string '{folder}' by the current folder in the notmuch query. This avoid to duplicate the same rule on each folder. 

For exemple : 

    [MailMover]
    folders = .Lists.firstlist .Lists.secondlist

    \.Lists\..* =
        'tag:spam':.Junk
        '(NOT tag:spam) AND (NOT folder:.Archive{folder}) AND tag:archives':.Archive{folder}

    ...