Add Lark

[erezsh]

What is this Python project?

Lark is a general-purpose parsing toolkit.

What's the difference between this Python project and similar ones?

Lark is already skyrocketing in popularity, compared to the competition: https://star-history.t9t.io/#lark-parser/lark&dabeaz/ply

It's much friendlier to beginners, with a better interface.

It can do a lot of things that PLY, and others, can't, like parsing natural language.

It also lets you generate a standalone parser, which is pretty unique.

[erezsh]

@vinta Hi, we have 20 votes. Is that enough to get this merged? Thanks

[blakev]

Approve

[cybergrind]

@vinta friendly ping, looks like this PR has reached the goal and deserves to be merged