d.ts not updated

[eyal1990]

The d.ts of the project is not updated.
The main problem is the inclusion of this line:

import React = __React;

When using @types/react there is no global variable named __React and so this file breaks the build.
The solution is kind of easy - omit the d.ts file from the project.
This way, whoever wants to use the d.ts will use @types/react-custom-scrollbars which don't use the global __React variable.

(In a way, inserting the d.ts was a breaking change for everyone who used @types/react).

Let me know what you think.

[aalenliang]

+1 the .d.ts file in project breaks usage.

[malte-wessel]

I'm not quite familiar with TypeScript, would be cool if someone made a PR to fix this!

[aalenliang]

1. remove the index.d.ts file,
2. and delete
   "typings": "index.d.ts",
   section in package.json.

[aalenliang]

#135

[malte-wessel]

Fixed by #135