Generated parser compiles with TypeScript's strict mode

[yokljo]

Added any types where required, and also made a few interfaces where it was simple to do so.

[pjmolina]

Hi @yokljo
Thanks for the effort on typing it!
Is the pull request complete?
I tried your branch with npm test and then tsc --strict output/arithmetics.ts with the following result.

On the other hand, forcing strict mode compile into more complex samples:

• output/css.ts
• output/json.ts
• output/javascript.ts
• output/st.ts
  hangs the TS compiler. I think it is a bug into the TS compiler related to this one already reported: TS 17033.

Looks like pegjs medium-size generated parsers are hard to digest for the TS compiler.

[yokljo]

Ah sorry, my sample size was 1: The grammar I wrote for my own project.
I'll see what I can do. Adding all the appropriate types required for the tests should definitely be doable.

[yokljo]

Now all the tests pass. I think that css.pegjs example is lost cause for now... I can't be bothered debugging the Typescript compiler.