Standardize shebang and coding declaration

Standardizes shebang and coding declarations.

Coding matches what's used by install tools such as pip(x).

Removes a few init files that were not needed.

bdfr/archive_entry/base_archive_entry.py

@@ -1,5 +1,5 @@
 #!/usr/bin/env python3
-# coding=utf-8
+# -*- coding: utf-8 -*-
 
 from abc import ABC, abstractmethod
 from typing import Union