clean etherlab: pep8, E741 ambiguous variable name 'l'

cleanup etherlab: pep8, E306 expected 1 blank line before a nested definition, found X

cleanup etherlab: pep8, E305 expected 2 blank lines after class or function definition, found X

cleanup etherlab: pep8, E201 whitespace after '('

cleanup etherlab: pep8, E202 whitespace before ')'

cleanup etherlab: pep8, E227 missing whitespace around bitwise or shift operator

cleanup etherlab: pep8, E251 unexpected spaces around keyword / parameter equals

cleanup etherlab: pep8, E225 missing whitespace around operator

cleanup etherlab: pep8, E303 too many blank lines (2)

cleanup etherlab: pep8, E231 missing whitespace after ','

cleanup etherlab: pep8, E271 multiple spaces after keyword

cleanup etherlab: pep8, E261 at least two spaces before inline comment

cleanup etherlab: pep8, E302 expected 2 blank lines, found 1

cleanup etherlab: pep8, W293 blank line contains whitespace