Use tokenizer browser

[Borewit]

Part of implementation of #248

Add browser specific functions.

Get file type based on content from Web API ReadableStream:

const FileType = require('file-type/browser');
(async () => {

    const response = await fetch("https://www.example.org/");
    const fileType = await FileType.fromStream(response.body);
})();

Get file type based on content from Blob:

const FileType = require('file-type/browser');
(async () => {
    const fileType = await FileType.fromBlob(blob);
})();

[Borewit]

Do you mind merging #261 & #262 first @sindresorhus? I am getting a little bit dizzy with all those outstanding PR's. Thanks a lot a for your detailed feedback, I know reviewing reviewing is lot of work.

[sindresorhus]

Done :)

[Borewit]

Okay, I cleaned up a bit.

I created to small PR with some fixing changes already merge (to prevent things getting mixed up):

• Fix waiting for ignore to be completed #274: Fixing some promise handling
• Fix duplicate name using module instance & file-type result. #275: Fixing README, fileType vs FileType

Than there is #265 preceding this PR, which move most functionality from index.js to core.js, which make core.js a polymorphic core (can be used by Node.js & browser). No rocket science, it essentially prevents a dependency on fs which is pretty Node.js specific.

At last there is this PR, #268, which adds browser functions and corresponding dependencies. If you change your mind, as the change is more clear, and prefer moving to a separate module, this is a good escape point.
Yet another module to maintain, at the other hand it maybe easier to add browser unit tests and prevent browser specific dependencies to end up in the Node dependency tree.

[sindresorhus]

This looks good too when you fix the merge conflict.