Isort

- Improved text of skipped file message to mention gitignore feature.
- Made all exceptions pickleable.
- Fixed 1779: Pylama integration ignores pylama specific isort config overrides.
- Fixed 1781: `--from-first` CLI flag shouldn't take any arguments.
- Fixed 1792: Sorting literals sometimes ignored when placed on first few lines of file.
- Fixed 1777: extend_skip is not honored wit a git submodule when skip_gitignore=true.

- Improved behavior of `isort --check --atomic` against Cython files.
- Fixed 1769: Future imports added below assignments when no other imports present.
- Fixed 1772: skip-gitignore will check files not in the git repository.
- Fixed 1762: in some cases when skip-gitignore is set, isort fails to skip any files.
- Fixed 1767: Encoding issues surfacing when invalid characters set in `__init__.py` files during placement.
- Fixed 1771: Improved handling of skips against named streamed in content.

- Fixed 1758: projects with many files and skip_ignore set can lead to a command-line overload.

- Improved CLI startup time.
- Implemented 1697: Provisional support for PEP 582: skip `__pypackages__` directories by default.
- Implemented 1705: More intuitive handling of isort:skip_file comments on streams.
- Implemented 1737: Support for using action comments to avoid adding imports to individual files.
- Implemented 1750: Ability to customize output format lines.
- Implemented 1732: Support for custom sort functions.
- Implemented 1722: Improved behavior for running isort in atomic mode over Cython source files.
- Fixed (https://github.com/PyCQA/isort/pull/1695): added imports being added to doc string in some cases.
- Fixed (https://github.com/PyCQA/isort/pull/1714): in rare cases line continuation combined with tabs can output invalid code.
- Fixed (https://github.com/PyCQA/isort/pull/1726): isort ignores reverse_sort when force_sort_within_sections is true.
- Fixed 1741: comments in hanging indent modes can lead to invalid code.
- Fixed 1744: repeat noqa comments dropped when * import and non * imports exist from the same package.
- Fixed 1721: repeat noqa comments on separate from lines with force-single-line set, sometimes get dropped.

Goal Zero (Tickets related to aspirational goal of achieving 0 regressions for remaining 5.0.0 lifespan):
- Implemented 1394: 100% branch coverage (in addition to line coverage) enforced.
- Implemented 1751: Strict typing enforcement (turned on mypy strict mode).

- Fixed 1631: as import comments can in some cases be duplicated.
- Fixed 1667: extra newline added with float-to-top, after skip, in some cases.
- Fixed 1594: incorrect placement of noqa comments with multiple from imports.
- Fixed 1566: in some cases different length limits for dos based line endings.
- Implemented 1648: Export MyPY type hints.
- Implemented 1641: Identified import statements now return runnable code.
- Implemented 1661: Added "wemake" profile.
- Implemented 1669: Parallel (`-j`) now defaults to number of CPU cores if no value is provided.
- Implemented 1668: Added a safeguard against accidental usage against /.
- Implemented 1638 / 1644: Provide a flag `--overwrite-in-place` to ensure same file handle is used after sorting.
- Implemented 1684: Added support for extending skips with `--extend-skip` and `--extend-skip-glob`.
- Implemented 1688: Auto identification and skipping of some invalid import statements.
- Implemented 1645: Ability to reverse the import sorting order.
- Implemented 1504: Added ability to push star imports to the top to avoid overriding explicitly defined imports.
- Documented 1685: Skip doesn't support plain directory names, but skip_glob does.

- Fixed 1612: In rare circumstances an extra comma is added after import and before comment.
- Fixed 1593: isort encounters bug in Python 3.6.0.
- Implemented 1596: Provide ways for extension formatting and file paths to be specified when using streaming input from CLI.
- Implemented 1583: Ability to output and diff within a single API call to `isort.file`.
- Implemented 1562, 1592 & 1593: Better more useful fatal error messages.
- Implemented 1575: Support for automatically fixing mixed indentation of import sections.
- Implemented 1582: Added a CLI option for skipping symlinks.
- Implemented 1603: Support for disabling float_to_top from the command line.
- Implemented 1604: Allow toggling section comments on and off for indented import sections.