Initial python3 changes

Mostly just updating libraries, removing string encoding/decoding,
fixing some edge cases. No new functionality was added in this
commit.

lib/beetsplug/freedesktop.py

@@ -0,0 +1,35 @@
+# This file is part of beets.
+# Copyright 2016, Matt Lichtenberg.
+#
+# 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.
+
+"""Creates freedesktop.org-compliant .directory files on an album level.
+"""
+
+
+from beets.plugins import BeetsPlugin
+from beets import ui
+
+
+class FreedesktopPlugin(BeetsPlugin):
+    def commands(self):
+        deprecated = ui.Subcommand(
+            "freedesktop",
+            help="Print a message to redirect to thumbnails --dolphin")
+        deprecated.func = self.deprecation_message
+        return [deprecated]
+
+    def deprecation_message(self, lib, opts, args):
+        ui.print_("This plugin is deprecated. Its functionality is "
+                  "superseded by the 'thumbnails' plugin")
+        ui.print_("'thumbnails --dolphin' replaces freedesktop. See doc & "
+                  "changelog for more information")