Black

- added `--quiet` (78)

- added automatic parentheses management (4)

- added [pre-commit](https://pre-commit.com) integration (#103, 104)

- fixed reporting on `--check` with multiple files (101, 102)

- fixed removing backslash escapes from raw strings (100, 105)

- added `--diff` (87)

- add line breaks before all delimiters, except in cases like commas, to better comply
with PEP 8 (73)

- standardize string literals to use double quotes (almost) everywhere (75)

- fixed handling of standalone comments within nested bracketed expressions; _Black_
will no longer produce super long lines or put all standalone comments at the end of
the expression (22)

- fixed 18.3a4 regression: don't crash and burn on empty lines with trailing whitespace
(80)

- fixed 18.3a4 regression: ` yapf: disable` usage as trailing comment would cause
_Black_ to not emit the rest of the file (95)

- when CTRL+C is pressed while formatting many files, _Black_ no longer freaks out with
a flurry of asyncio-related exceptions

- only allow up to two empty lines on module level and only single empty lines within
functions (74)

- ` fmt: off` and ` fmt: on` are implemented (5)

- automatic detection of deprecated Python 2 forms of print statements and exec
statements in the formatted file (49)

- use proper spaces for complex expressions in default values of typed function
arguments (60)

- only return exit code 1 when --check is used (50)

- don't remove single trailing commas from square bracket indexing (59)

- don't omit whitespace if the previous factor leaf wasn't a math operator (55)

- omit extra space in kwarg unpacking if it's the first argument (46)

- omit extra space in
[Sphinx auto-attribute comments](http://www.sphinx-doc.org/en/stable/ext/autodoc.html#directive-autoattribute)
(68)

- don't remove single empty lines outside of bracketed expressions (19)

- added ability to pipe formatting from stdin to stdin (25)

- restored ability to format code with legacy usage of `async` as a name (20, 42)

- even better handling of numpy-style array indexing (33, again)

- changed positioning of binary operators to occur at beginning of lines instead of at
the end, following
[a recent change to PEP 8](https://github.com/python/peps/commit/c59c4376ad233a62ca4b3a6060c81368bd21e85b)
(21)

- ignore empty bracket pairs while splitting. This avoids very weirdly looking
formattings (34, 35)

- remove a trailing comma if there is a single argument to a call

- if top level functions were separated by a comment, don't put four empty lines after
the upper function

- fixed unstable formatting of newlines with imports

- fixed unintentional folding of post scriptum standalone comments into last statement
if it was a simple statement (18, 28)

- fixed missing space in numpy-style array indexing (33)

- fixed spurious space after star-based unary expressions (31)

- added `--check`

- only put trailing commas in function signatures and calls if it's safe to do so. If
the file is Python 3.6+ it's always safe, otherwise only safe if there are no `*args`
or `**kwargs` used in the signature or call. (8)

- fixed invalid spacing of dots in relative imports (6, 13)

- fixed invalid splitting after comma on unpacked variables in for-loops (23)

- fixed spurious space in parenthesized set expressions (7)

- fixed spurious space after opening parentheses and in default arguments (14, 17)

- fixed spurious space after unary operators when the operand was a complex expression
(15)