Implement code linting and use best practices

[dvzrv]

The codebase seems to not be linted at all. This is very easily done using pep8, will improve and therefore make it easier for outsiders to do pull requests.

A very versatile tool for automated testing is tox, that can help you automate running tests on your codebase (tests will keep you from breaking stuff horribly) on multiple python (major/minor/patch) versions.

This automated process can even be done on every pull request or on a schedule, using pipeline tools, such as travis.

[Houston4444]

I made a big code re-organization. I separated code between gui, daemon and clients. I tried to lint all (except in 'clients', I didn't check).