Update beets to 1.3.18:

Dependencies:
* PyYAML 3.11
* Unidecode 0.4.19
* beets 1.3.18
* colorama 0.3.7
* enum34 1.1.6
* jellyfish 0.5.4
* munkres 1.0.7
* musicbrainzngs 0.6
* mutagen 1.32

libs/beetsplug/filefilter.py

@@ -0,0 +1,78 @@
+# -*- coding: utf-8 -*-
+# This file is part of beets.
+# Copyright 2016, Malte Ried.
+#
+# Permission is hereby granted, free of charge, to any person obtaining
+# a copy of this software and associated documentation files (the
+# "Software"), to deal in the Software without restriction, including
+# without limitation the rights to use, copy, modify, merge, publish,
+# distribute, sublicense, and/or sell copies of the Software, and to
+# permit persons to whom the Software is furnished to do so, subject to
+# the following conditions:
+#
+# The above copyright notice and this permission notice shall be
+# included in all copies or substantial portions of the Software.
+
+"""Filter imported files using a regular expression.
+"""
+
+from __future__ import division, absolute_import, print_function
+
+import re
+from beets import config
+from beets.plugins import BeetsPlugin
+from beets.importer import SingletonImportTask
+
+
+class FileFilterPlugin(BeetsPlugin):
+    def __init__(self):
+        super(FileFilterPlugin, self).__init__()
+        self.register_listener('import_task_created',
+                               self.import_task_created_event)
+        self.config.add({
+            'path': '.*'
+        })
+
+        self.path_album_regex = \
+            self.path_singleton_regex = \
+            re.compile(self.config['path'].get())
+
+        if 'album_path' in self.config:
+            self.path_album_regex = re.compile(self.config['album_path'].get())
+
+        if 'singleton_path' in self.config:
+                self.path_singleton_regex = re.compile(
+                    self.config['singleton_path'].get())
+
+    def import_task_created_event(self, session, task):
+        if task.items and len(task.items) > 0:
+            items_to_import = []
+            for item in task.items:
+                if self.file_filter(item['path']):
+                    items_to_import.append(item)
+            if len(items_to_import) > 0:
+                task.items = items_to_import
+            else:
+                # Returning an empty list of tasks from the handler
+                # drops the task from the rest of the importer pipeline.
+                return []
+
+        elif isinstance(task, SingletonImportTask):
+            if not self.file_filter(task.item['path']):
+                return []
+
+        # If not filtered, return the original task unchanged.
+        return [task]
+
+    def file_filter(self, full_path):
+        """Checks if the configured regular expressions allow the import
+        of the file given in full_path.
+        """
+        import_config = dict(config['import'])
+        if 'singletons' not in import_config or not import_config[
+                'singletons']:
+            # Album
+            return self.path_album_regex.match(full_path) is not None
+        else:
+            # Singleton
+            return self.path_singleton_regex.match(full_path) is not None