Don't need 2to3 imports fixer now.

These are all false positives:

$ 2to3 --no-diffs -n -w -f imports Bio BioSQL Tests Doc Scripts
...
RefactoringTool: Files that were modified:
RefactoringTool: Bio/_six.py
RefactoringTool: Bio/_py3k/__init__.py
RefactoringTool: Tests/run_tests.py
RefactoringTool: Doc/examples/getgene.py
RefactoringTool: Doc/examples/www_blast.py
RefactoringTool: Scripts/GenBank/check_output.py
RefactoringTool: Scripts/xbbtools/xbb_blast.py
RefactoringTool: Scripts/xbbtools/xbb_blastbg.py
RefactoringTool: Scripts/xbbtools/xbb_help.py
RefactoringTool: Scripts/xbbtools/xbb_search.py
RefactoringTool: Scripts/xbbtools/xbb_translations.py
RefactoringTool: Scripts/xbbtools/xbb_utils.py
RefactoringTool: Scripts/xbbtools/xbb_widget.py
RefactoringTool: Scripts/xbbtools/xbbtools.py

$ 2to3 --no-diffs -n -w -f imports -d Bio BioSQL Tests Doc Scripts
...
RefactoringTool: Files that were modified:
RefactoringTool: Bio/bgzf.py
RefactoringTool: Bio/SeqIO/SffIO.py
RefactoringTool: Bio/SeqIO/__init__.py
Don't need 2to3 instances fixer now.

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

$ 2to3 --no-diffs -n -w -f isinstance Bio BioSQL Tests Doc Scripts
...
(makes no changes, seems to consider it for a few files - odd)