Apply 2to3 reduce fixer (not a builtin on Python 3)

$ 2to3 --no-diffs -n -w -f reduce Bio BioSQL Tests Doc Scripts
Skip assorted 2to3 fixers which shouldn't be needed anymore

If new code or changes accidentally break under Python 3,
then hopefully our unit tests will catch that... meanwhile
this should make running 2to3 faster.
Switch do2to3.py to list desired fixers

This makes it easier to see what issues remain for
running all of Biopython as dual Python 2 and 3 code.
Disable assorted 2to3 fixers which we don't need (anymore)

$ 2to3 --no-diffs -n -w -f apply Bio BioSQL Tests Doc Scripts
RefactoringTool: No files need to be modified.

etc