Autopep8

* changes
* requirement pycodestyle version 2.6.0+ ( 548 )
* fix bugs
* Expected pyproject.toml configuration syntax incompatible with TOML format ( 528 , 546 )
* Fix incompatible exit code with --jobs=0 and --exit-code ( 543 , 545 )
* Fix hangup E122 fixed method with backslash ( 540 , 541 )

* new features
* 480, 535 : support parallel jobs for diff option
* changes
* 501, 537 : enable exclude option when specify directly file args
* fix bugs
* 364, 538 : related code E702
* 533 : related code W503/W504

* fix bugs
* 525 : related code W503 and W504 (Thanks NovaDev94)
* 526 : return diff exit code when reading from stdin too (Thanks pvxe )
* 529, 530 : related code E402
* 518, 532 : related code W503 and W504

* Support Python3.8
* Support `pyproject.toml` with `[tool.autopep8]` section.
* fix bugs
* 503, 511 : related code W503
* 486, 488 : related code E117
* 489, 498 : related code E711/E712
* 449, 514 : related code W605

* fix bugs
* 456, 466 : related code W504/3 (Thanks asottile )
* 463, 464 : related code W504 (Thanks bagerard )
* 461, 467 : related code E402 (Thanks Hanaasagi )
* Improved
* 457 : Don't write the file unless there are changes (Thanks asottile )
* 478 : update configuration documentation (Thanks Ch00k )

fix bugs

* 449 (PR: 450) : related code W605 (Thanks to patch by bigredengineer)
* 447 : related code E402
* 446 : related code W503