Add documentation to set up editors with pep8

failing GpuConv unittest

Minor stuff

added new sparse ops in sanbox

PEP 8 fixes, assisted by Syntastic and flake8.

Remove obsolete :api: role, and replace refs.

Also removes now unused scripts.

Better exceptions

This error was previously caught as a MissingInputException.

Use sys.executable instead of 'python'

This way, the same executable will be used.

Add err

Minor stuff