Replace @properties, consider using attrs

[c24t]

Many classes needlessly wrap attributes in @propertys, e.g.

class Foo(object):
    def __init__(bar):
        self._bar = bar

    @property
    def bar(self):
        """The current bar value"""
        return self._bar

These should be replaced with plain old attributes.

While we're doing this, we should consider using the attrs library, which would let us remove some boilerplate code and provides AutoValue-style immutable value classes when we actually do want to protect certain attributes.

However, using attrs would mean adding a dependency on another third party library and making the code less readable (and more magical).