Please support python 3 abstract methods
bro-bro...Python is a dynamic language. Peewee uses this dynamism to provide such nice (if I do say so myself) APIs. There will be no ABCs. Hi, I'm rather disappointed in this response for a number of reasons.

At the very least I would like to be able to run pylint against peewee without getting a bunch of spurious E1111 notifications, and there are many mechanisms that peewee could use to provide that ability. ABCs were the most readily-obvious ones but there are other approaches as well.

I also don't really care for the condescending tone of your response. I realize that peewee is a volunteer effort that you do for your own needs but it's also part of a greater ecosystem.

Also, I'm not a bro.
Since Python 3.4, there has been a mechanism for declaring abstract base classes and methods thereof, from the [`abc` module](https://docs.python.org/3/library/abc.html). As of Python 3.7, pylint pretty much requires its use; for example, the line:

    self._query = model.Entry.select().where(self._where)

results in the pylint error:

    publ/view.py:89:8: E1111: Assigning to function call which doesn't return (assignment-from-no-return)

As a temporary measure I can simply disable that warning from pylint, but going forward it would be great if peewee were to use `abc.abstractmethod` and `abc.ABC` to suppress these errors and provide abstract base classes in a more declarative, linter-friendly way.
