[Biopython] Adopting black for Python code style

[Peter Cock]

Dear Biopythoneers,

As you may be aware from the Biopython Project Update 2019 talk
at BOSC 2019, or the CoFest, or associated discussions, we have
been discussing adopting the "black" Python code style for Biopython:

https://github.com/biopython/biopython/issues/2008

None of us seem to like everything about the convention, but the
advantages of a single automated code style outweigh this.

Unless there are objections (particularly from the active contributors),
I am proposing we start to run black on a module by module basis
in order to allow human review of the changes. In particular, comment
placement may need fixing, and in rare cases like data structures we
may want to disable the black formatting for a section of code.

I'm suggesting giving it until the end of August 2019 for people to
raise an objection?

Thank you all,

Peter