ecube datasource compatibility with ecube recording

[leoscholl]

having trouble getting the ecube datasource to play nicely with the recording feature.

Headstage channels added:
(array([7, 7], dtype=uint32), array([1, 2], dtype=uint32))
AnalogPanel channels added:
[ 1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
 25 26 27 28 29 30 31 32]
DigitalPanel channels added:
[ 1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48
 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64]
Started streaming from ecube
Process ecube:
Traceback (most recent call last):
  File "/usr/local/lib/python3.7/multiprocessing/process.py", line 297, in _bootstrap
    self.run()
  File "/home/pagaiisland/leo/bmi3d/riglib/source.py", line 365, in run
    chan, data = system.get()
  File "/home/pagaiisland/leo/bmi3d/riglib/ecube/__init__.py", line 92, in get
    return next(self.gen)
  File "/home/pagaiisland/leo/bmi3d/riglib/ecube/__init__.py", line 13, in multi_chan_generator
    yield (channels[idx], data_block[::downsample,idx]) # yield one channel at a time
IndexError: list index out of range