Completed code linting

All code modules are now linted and conform to PEP8 (the definitive Python style guide).

pylint was used with a standard pylintrc file. Maximum line length was changed from 80 to 120 chars.

Where code could not conform to PEP8, the relevant pylint warning was disabled.

Future code changes should endeavour to maintain conformity with PEP8 to the fullest extent possible.

Disabled warnings should be reviewed to determine if the code can be refactored to allow that warning.