Detect pep-0263

[patrikha]

It would be great if the following header is supported:

#! /usr/bin/env python
# -*- coding: utf-8 -*-

please see:
pep-0263

hax workaround:

def get_encoding(path):
    if not isinstance(path, Path):
        path = Path(path)
    with open(path, 'rb') as stream:
        raw_bytes = stream.read(1024)
    encoding = chardet.detect(raw_bytes)['encoding']
    if path.suffix.lower() == '.py':
        start_pos = raw_bytes.find(b'-*- coding: ')
        if start_pos != -1:
            start_pos += 12
            end_pos = raw_bytes[start_pos:].find(b' -*-')
            if end_pos:
                end_pos += start_pos
                coding = raw_bytes[start_pos:end_pos]
                encoding = coding.decode(encoding)
    return encoding