Lark-parser

- Added error handling to LALR!
- `on_error` option to `Lark.parse()`.
Read here: https://lark-parser.readthedocs.io/en/latest/classes/#larkparse
- Parser now comes with a puppet for advanced error handling.
Read here: https://lark-parser.readthedocs.io/en/latest/classes/#parserpuppet

- Support for better regexps with the `regex` module, when using `Lark(..., regex=True)`
Read here: https://lark-parser.readthedocs.io/en/latest/classes/#using-unicode-character-classes-with-regex

The last two releases were wrong. I apologize.

Hopefully that's the last of it, and we'll be back on track with periodic and accurate releases.

The main features for this release:

* **Grammar caching**: It's now possible to cache the results of the LALR grammar analysis, for x2 to x3 faster loading. Use `Lark(..., cache=True)` or specify a file name. See here: https://lark-parser.readthedocs.io/en/latest/classes/

* **Grammar templates**: Added support for grammar "functions" that expand in preprocessing. No docs yet, but see here for examples:
https://github.com/lark-parser/lark/blob/master/tests/test_parser.py#L845

* **Lark online IDE**: Technically not a feature, but it's possible to run Lark in the browser. Now we also have a simple IDE on github pages: https://lark-parser.github.io/lark/ide/app.html

* Other changes:

* Improved performance for large grammars

* More debug prints when in debug mode

* Better support for PyInstaller

* Lots of bugfixes: mypy stubs, v_args, docs, and more.