be able to have an empty title

Author: smahot

pymkv/MKVFile.py

@@ -154,7 +154,7 @@ def command(self, output_path, subprocess=False):
 
         output_path = expanduser(output_path)
         command = [self.mkvmerge_path, '-o', output_path]
-        if self.title:
+        if self.title is not None:
             command.extend(['--title', self.title])
         # add tracks
         for track in self.tracks: