Improve typings

[delvedor]

With this change, it's now easier to use TypeScript with the client.
The ApiResponse now accepts a generics that defaults to any, same for every API method that might need a body.

The documentation has been updated accordingly.

I would like to thank @fox1t for the suggestions :)

[fox1t]

LGTM

[DASPRiD]

I'm wondering, why can't this part be exported by this client library directly? This seems generic enough.

[delvedor]

Because there is not an official spec from which I can generate the response types, and it will make no sense export the types just for the search response.

[DASPRiD]

"interface", not "intefrace" ;)

[onehorsetown]

Shouldn't ApiMethod be typed like this, so if you are using promises and you are okay with body: any, you don't have to cast anything:

declare type callbackFn<T> = (
  err: Error | null,
  result: ApiResponse<T>
) => void;

interface ApiMethod<T, R = any> {
  (params: T, options?: TransportRequestOptions): Promise<ApiResponse<R>>;
  (params: T, callback: callbackFn<R>): void;
  (params: T, options: TransportRequestOptions, callback: callbackFn<R>): void;
}