Remove unused imports
Ensure two blank lines between functions

This makes pep8 happy and enforces a uniform coding style.
Make inline comments start with a space
Fix indentation
Shorten long lines
Wrap long line in comment
Import futures from concurrent

This allows us to have shorter lines in the code and thus fix the
remaining problems reported by pep8.
Merge pull request #1 from mgeisler/style-issues

Style issues