* WIP: Add failing test for a matlab class with properties.

* Add some missing keywords

* Add leading \s* matchers to things above the command form regex, as it tends to swallow keywords otherwise.

* Add support for the special 'properties' block syntax.

* Fix apparent infinite loop when given garbage input.

* Use includes to clean up some of my copypasta.

* Fix negative lookahead when there's more than one space between operators.

* Use Whitespace not Text for spaces; combine adjacent whitespace.

* Add support for declarative property constraints.

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>

* Add analyze_text to make make check happy.

This also fixes a few small bugs:

* Slash uses *.sla as the file ending, not *.sl
* IDL has endelse, not elseelse

* Improve various analyse_text methods.

* Improve various analyse_text methods.

* Make Perl less confident in presence of :=.
* Improve brainfuck check to not parse the whole input.
* Improve Unicon by matching \self, /self
* Fix Ezhil not matching against the input text

* Simplify Modula2::analyse_text.

* Add explicit line continuation for Matlab session

Matlab lines can be explicitly continued with the ... syntax at the end
of a line. In the Session lexer, this requires continuing to the next
line to add more text. Otherwise, the next line is marked as output.

* The ellipses in Matlab should be a Keyword

The built-in Matlab syntax highlighter highlights ... with the same
formatting as a keyword. Everything after that on the line should be a
comment.

* Update Matlab functions and keywords from R2018a

* Fix many spaces in assignment formatted as string

In command mode, MATLAB allows mutiple space separated arguments to a
function which are interpreted as char arrays, and are formatted as
Strings. This check was also catching cases where there were multiple
spaces following an assignment or comparison operation and formatting
the rest of the line as a string. Now, if an = or operator is found, the
commandargs state is popped and control returns to the root state.

* Add tests for MATLAB formatting