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/random.py

@@ -0,0 +1,81 @@
+# -*- coding: utf-8 -*-
+# This file is part of beets.
+# Copyright 2016, Philippe Mongeau.
+#
+# 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.
+
+"""Get a random song or album from the library.
+"""
+from __future__ import division, absolute_import, print_function
+
+from beets.plugins import BeetsPlugin
+from beets.ui import Subcommand, decargs, print_
+import random
+from operator import attrgetter
+from itertools import groupby
+
+
+def random_item(lib, opts, args):
+    query = decargs(args)
+
+    if opts.album:
+        objs = list(lib.albums(query))
+    else:
+        objs = list(lib.items(query))
+
+    if opts.equal_chance:
+        # Group the objects by artist so we can sample from them.
+        key = attrgetter('albumartist')
+        objs.sort(key=key)
+        objs_by_artists = {}
+        for artist, v in groupby(objs, key):
+            objs_by_artists[artist] = list(v)
+
+        objs = []
+        for _ in range(opts.number):
+            # Terminate early if we're out of objects to select.
+            if not objs_by_artists:
+                break
+
+            # Choose an artist and an object for that artist, removing
+            # this choice from the pool.
+            artist = random.choice(objs_by_artists.keys())
+            objs_from_artist = objs_by_artists[artist]
+            i = random.randint(0, len(objs_from_artist) - 1)
+            objs.append(objs_from_artist.pop(i))
+
+            # Remove the artist if we've used up all of its objects.
+            if not objs_from_artist:
+                del objs_by_artists[artist]
+
+    else:
+        number = min(len(objs), opts.number)
+        objs = random.sample(objs, number)
+
+    for item in objs:
+        print_(format(item))
+
+random_cmd = Subcommand('random',
+                        help=u'chose a random track or album')
+random_cmd.parser.add_option(
+    u'-n', u'--number', action='store', type="int",
+    help=u'number of objects to choose', default=1)
+random_cmd.parser.add_option(
+    u'-e', u'--equal-chance', action='store_true',
+    help=u'each artist has the same chance')
+random_cmd.parser.add_all_common_options()
+random_cmd.func = random_item
+
+
+class Random(BeetsPlugin):
+    def commands(self):
+        return [random_cmd]