Improve exported types definition for v2 to include Parser namespace

[mradcliffe]

This is a follow-up from #272.

I tried out the typings is 2.0.0, but it seems like the typings aren't usable except for a very limited use case. Typescript version 3.2.2 reported in Visual Studio Code.

For instance, I can do the following:

import { parse } from 'bowser';

// browser.os.name autocompletes here in Code.
const browser = parse(window.navigator.userAgent);

but I cannot type the variables themselves:

// Errors out because Parser.ParsedDetail is not available.
const browser: Parser.ParsedDetail = parse(window.navigator.userAgent);

This may not seem important in that example, but it is important in a class context:

class Blah {
  // This cannot be assigned a type because Parser is not available as an export.
  // Leaving it as "any" means that no type completion is available in a IDE so a
  // developer has to memorize the API.
  browser: Parser.ParsedDetail;

  constructor() {
    this.browser = parse(window.navigator.userAgent);
  }
}

Basically anything other than getParser and parse cannot be used as types. This seems to correspond to comment in #277:

I think and I've tried 😂 this should be the stable version, but the only thing I don't know yet is if through these typings, users could maybe access to Parser as definition even if they cannot in real. I have to test this aspect.

I tried hacking in export as namespace Parser;, but I couldn't import it. I'm not really good at creating typings so I had to take all the Parser namespace and paste it into my typings.d.ts file to workaround this.

[lancedikson]

Hi, @mradcliffe. I'm not that good at typings either to answer correctly, but I'm diving into TypeScript nowadays, so, I hope, I'll be able to improve it exporting all the needed types :)

[lancedikson]

Ok, now I see the problem. We don't export those auxiliary types from the typing declaration file. So, it seems that we can do that. And, actually, namespaces seem a bit useless. I'll try to review the typings this weekend and hopefully come up with a bulletproof solution.

[JaceHensley]

@lancedikson I'm gonna put a PR shortly to do this

[JaceHensley]

#289

[lancedikson]

Forgot to close this one after merging the PR