MailMover: preserve maildir subdir

Currently, MailMover moves all mail to `/cur`. But everyone moving mail
from `/new` to `/cur` is required to set up the maildir flags field in
the name.

Rather than setting up that field, preserve the maildir subdir part and
let other clients change subdirs as necessary. After all, "moving" does
not constitute "reading".

afew/MailMover.py

@@ -34,6 +34,7 @@ def __init__(self, max_age=0, rename = False, dry_run=False):
 
     def get_new_name(self, fname, destination):
         basename = os.path.basename(fname)
+        submaildir =  os.path.split(os.path.split(fname)[0])[1]
         if self.rename:
             parts = basename.split(':')
             if len(parts) > 1:
@@ -43,7 +44,7 @@ def get_new_name(self, fname, destination):
                             # construct a new filename, composed of a made-up ID and the flags part
                             # of the original filename.
             basename = str(uuid.uuid1()) + flagpart
-        return os.path.join(destination, basename)
+        return os.path.join(destination, submaildir, basename)
 
     def move(self, maildir, rules):
         '''
@@ -54,7 +55,7 @@ def move(self, maildir, rules):
         to_delete_fnames = []
         moved = False
         for query in rules.keys():
-            destination = '{}/{}/cur/'.format(self.db_path, rules[query])
+            destination = '{}/{}/'.format(self.db_path, rules[query])
             main_query = self.query.format(folder=maildir, subquery=query)
             logging.debug("query: {}".format(main_query))
             messages = notmuch.Query(self.db, main_query).search_messages()