[GTK3] Fix Python 3 issues

In Python 3 builtin next function instead of the next method.

Unpickling with translated strings in state file causes ascii decode
error so ensure UTF-8 encoding is specified.

deluge/path_chooser_common.py

@@ -12,6 +12,8 @@ from __future__ import unicode_literals
 
 import os
 
+from deluge.common import PY2
+
 
 def is_hidden(filepath):
     def has_hidden_attribute(filepath):
@@ -52,7 +54,10 @@ def get_completion_paths(args):
 
     def get_subdirs(dirname):
         try:
-            return os.walk(dirname).next()[1]
+            if PY2:
+                return os.walk(dirname).__next__[1]
+            else:
+                return next(os.walk(dirname))[1]
         except StopIteration:
             # Invalid dirname
             return []

deluge/ui/gtk3/common.py

@@ -29,7 +29,7 @@ from gi.repository.Gtk import (
     SortType,
 )
 
-from deluge.common import get_pixmap, osx_check, windows_check
+from deluge.common import PY2, get_pixmap, osx_check, windows_check
 
 log = logging.getLogger(__name__)
 
@@ -331,7 +331,10 @@ def load_pickled_state_file(filename):
         log.info('Opening %s for load: %s', filename, _filepath)
         try:
             with open(_filepath, 'rb') as _file:
-                state = pickle.load(_file)
+                if PY2:
+                    state = pickle.load(_file)
+                else:
+                    state = pickle.load(_file, encoding='utf8')
         except (IOError, pickle.UnpicklingError) as ex:
             log.warning('Unable to load %s: %s', _filepath, ex)
         else: