fix unnecessary lambda and enable corresponding pylint check

fix wrong-import-order. first standard modules are imported, then others

fix (old-style-class) Old-style class defined error for most parts of
the code

only PyJS code is left, because it does some fancy tricks and can't be
easily fixed. So far PyJS doesn't support Python3 anyway.

remove in-tree version of Zeroconf and use upstream from
python-zeroconf package

remove reimported modules

fix unnecessary parens after keyword