Fix Tkinter imports on Python 3

[musicinmybrain]

I didn’t attempt to test this interactively, but this at least allows python3 -c 'import plac_tk' to succeed.

[ialbert]

I have never used the Tkinter based functionality myself - and since it does not work on Python 3 it means nobody else using Python 3 used it either. Maybe the better solution would be to deprecate this functionality.

[musicinmybrain]

I have never used the Tkinter based functionality myself - and since it does not work on Python 3 it means nobody else using Python 3 used it either. Maybe the better solution would be to deprecate this functionality.

I think that’s very sensible. If it has been broken for years and nobody has complained, it’s probably not worthwhile to keep shipping it.

I discovered this when I added an importability test to the python-plac package in Fedora, which I maintain as an indirect dependency for https://github.com/snakemake/snakemake via https://github.com/yte-template-engine/yte.