Maildir.__init__():  Make sure self.boxes is set.

This closes SourceForge bug #117490.
diff --git a/Lib/mailbox.py b/Lib/mailbox.py
index 51aeb30..c92e145 100755
--- a/Lib/mailbox.py
+++ b/Lib/mailbox.py
@@ -180,7 +180,6 @@
     # Qmail directory mailbox
 
     def __init__(self, dirname):
-        import string
         self.dirname = dirname
 
         # check for new mail
@@ -193,6 +192,8 @@
         boxes += [os.path.join(curdir, f)
                   for f in os.listdir(curdir) if f[0] != '.']
 
+        self.boxes = boxes
+
     def next(self):
         if not self.boxes:
             return None
@@ -225,7 +226,6 @@
 def _test():
     import time
     import sys
-    import string
     import os
 
     args = sys.argv[1:]
@@ -261,7 +261,7 @@
         if len(args) <= 1:
             msg.fp = None
     if len(args) > 1:
-        num = string.atoi(args[1])
+        num = int(args[1])
         print 'Message %d body:'%num
         msg = msgs[num-1]
         msg.rewindbody()