Rendering to WAV using "dro_player -r" or "dro_split" throws an exception

[jestar jokin]

Exception is:

Traceback (most recent call last):
  File "E:\Apps\Programming\Python27\lib\threading.py", line 551, in __bootstrap_inner
    self.run()
  File "D:\temp\hg\DROTrimmer_v3\src\dro_player.py", line 45, in inner_func
    func(self, *args, **kwds)
  File "D:\temp\hg\DROTrimmer_v3\src\dro_player.py", line 484, in run
    self.dro_player.processing_streams.render(inst.value)
  File "D:\temp\hg\DROTrimmer_v3\src\dro_player.py", line 117, in render
    stream.render(ms_to_render)
  File "D:\temp\hg\DROTrimmer_v3\src\dro_player.py", line 250, in render
    if ostream.is_active():
AttributeError: 'WavRenderer' object has no attribute 'is_active'

This is due to a regression introduced in changeset 63fbecf98e9d; to avoid errors writing to a closed output stream, we first check if the stream is still active, however the WavRenderer doesn't implement an "is_active" method.

[jestar jokin]

Fixed in v4 r4.