Fix recent_files config option automatically

The recent_files list has to be an python object serialization. This object
must be an array of strings. Python will save unicode strings and Python3
strings. Not following this rule make m64py crash either while loading the
recent_files information or when adding a new entry when a file is opened.

Author: Fayvel Victor

src/m64py/frontend/recentfiles.py

@@ -49,9 +49,18 @@ def create(self):
         self.action_clear_history.triggered.connect(self.clear)
         self.parent.menuRecent.addAction(self.action_clear_history)
 
+    def is_string(self, obj):
+        try:
+            return isinstance(obj, basestring)
+        except NameError:
+            return isinstance(obj, str)
+
     def update(self):
         """Updates list of recent files."""
         self.recent_files = self.parent.settings.qset.value("recent_files", [])
+        if not type(self.recent_files) == list:
+            self.recent_files = []
+        self.recent_files = list(filter(lambda x: self.is_string(x), self.recent_files))
         num_files = min(len(self.recent_files), self.max_recent)
         for i in range(num_files):
             text = QFileInfo(self.recent_files[i]).fileName()