* SQL whitespaces - regarding #1905

* Sqlite prompt ungrouped from trailing space

* sqlite prompt with Explicit trailing whitespace token

* Fix insertion of sqlite trail space token

pyupgrade is a tool to automatically upgrade syntax for newer versions
of the Python language.

The project has been Python 3 only since
35544e2fc6eed0ce4a27ec7285aac71ff0ddc473, allowing for several cleanups:

- Remove unnecessary "-*- coding: utf-8 -*-" cookie. Python 3 reads all
  source files as utf-8 by default.

- Replace IOError/EnvironmentError with OSError. Python 3 unified these
  exceptions. The old names are aliases only.

- Use the Python 3 shorter super() syntax.

- Remove "utf8" argument form encode/decode. In Python 3, this value is
  the default.

- Remove "r" from open() calls. In Python 3, this value is the default.

- Remove u prefix from Unicode strings. In Python 3, all strings are
  Unicode.

- Replace io.open() with builtin open(). In Python 3, these functions
  are functionally equivalent.

Co-authored-by: Matthäus G. Chajdas <Anteru@users.noreply.github.com>

* MySQL: Tokenize quoted schema object names, and escape characters, uniquely

Changes in this patch:

* Name.Quoted and Name.Quoted.Escape are introduced as non-standard tokens
* HTML and LaTeX formatters were confirmed to provide default formatting
  if they encounter these two non-standard tokens. They also add style
  classes based on the token name, like "n-Quoted" (HTML) or "nQuoted"
  (LaTeX) so that users can add custom styles for these.
* Removed "\`" and "\\" as schema object name escapes. These are relics
  of the previous regular expression for backtick-quoted names and are
  not treated as escape sequences. The behavior was confirmed in the
  MySQL documentation as well as by running queries in MySQL Workbench.
* Prevent "123abc" from being treated as an integer followed by a schema
  object name. MySQL allows leading numbers in schema object names as long
  as 0-9 are not the only characters in the schema object name.
* Add ~10 more unit tests to validate behavior.

Closes #1551

* Remove an end-of-line regex match that triggered a lint warning

Also, add tests that confirm correct behavior. No tests failed before
or after removing the '$' match in the regex, but now regexlint isn't
complaining.

Removing the '$' matching probably depends on the fact that Pygments
adds a newline at the end of the input text, so there is always something
after a bare integer literal.

* Overhaul the MySQL lexer

Fixes #975, #1063, #1453

Changes include:

Documentation
-------------

* Note in the lexer docstring that Oracle MySQL is the target syntax.
  MariaDB syntax is not a target (though there is significant overlap).

Unit tests
----------

* Add 140 unit tests for MySQL.

Literals
--------

* Hexadecimal/binary/date/time/timestamp literals are supported.
* Integer mantissas are supported for scientific notation.
* In-string escapes are now tokenized properly.
* Support the "unknown" constant.

Comments
--------

* Optimizer hints are now supported, and keywords are
  recognized and tokenized as preprocessor instructions.
* Remove nested multi-line comment support, which is no
  longer supported in MySQL.

Variables
---------

* Support the '@' prefix for variable names.
* Lift restrictions on characters in unquoted variable names.
  (MySQL does not impose a restriction on lead characters.)
* Support single/double/backtick-quoted variable names, including escapes.
* Support the '@@' prefix for system variable names.
* Support '?' as a variable so people can demonstrate prepared statements.

Keywords
--------

* Keyword / data type / function are now in a separate, auto-updating file.
* Support 25 additional data types (including spatial and JSON types).
* Support 460 additional MySQL keywords.
* Support 372 MySQL functions.
  Explicit function support resolves a bug that causes non-function
  items to be treated as functions simply because they have a trailing
  opening parenthesis.
* Support exceptions for the 'SET' keyword, which is both a datatype and
  a keyword depending on context.

Schema object names
-------------------

* Support Unicode in MySQL schema object names.
* Support parsing of backtick-quoted schema object name escapes.
  (Escapes do not produce a distinct token type at this time.)

Operators
---------

* Remove non-operator characters from the list of operators.
* Remove non-punctuation characters from the list of punctuation.

* Cleanup items based on feedback

* Remove an unnecessary optional newline lookahead for single-line comments