ImportError: No module named Spectrum2.iochannel

[tigre-bleu]

I try to run transwhat on debian stretch. For this I cloned the project from github and checked out the last release.
Launching spectrum fails with the following:

Traceback (most recent call last):
  File "/home/spectrum2/transwhat/transWhat/transwhat.py", line 40, in <module>
    from Spectrum2.iochannel import IOChannel
ImportError: No module named Spectrum2.iochannel

I could move the Spectrum2 folder to the same level as transwhat.py but then I have:

Traceback (most recent call last):
  File "/home/spectrum2/transwhat/transWhat/transwhat.py", line 41, in <module>
    from config import SpectrumConfig
ImportError: No module named config

I tried the master branch, but with no success.

I really struggle to have transwhat working. I also tried the spectrum2 docker image, but it does not work either.