Py7zr

Changed
-------

* extract: decompression is done as another process in default.
* extract: default multiprocessing mode is spawn
* extract: single process mode for password protected archive.

Fixed
-----

* extract: catch UnsupportedMethod exception properly when multiprocessing.

- A versions v0.3 - v0.6b1 has a problem on concurrency method.
It uses 'concurrency.futures' . If application uses it and call py7zr, it become freeze or dead lock.

This release replace it with 'multiprocessing.Process()'.

Changed
-------

* Concurrency implementation changes to use multiprocessing.Process() instead of
concurrency.futures to avoid freeze or deadlock with application usage of it.(70)
* Stop checking coverage because coverage.py > 5.0.0 produce error when multiprocessing.Process() usage.
* Drop handlers, NullHandler, BufferHnalder, and FileHander.

Known Issues
------------

* Extraction of encrypted archive which has multiple compression folders fails when
multiprocessing mode is not 'fork', that is python3.8 and later on MacOS, and on Windows.
see. test_extract_encrypted_2()

- User can extract selected files with 'extract()' method.
- Fix symbolic link extraction with relative target path.

Fixed
-----

* Fix _is_solid() method to return correct result.(72)