update nef api - carbon

[miguelangel-dev]

Description

To offer a better user experience, I have updated the API on how to consume Carbon.

Now, you do not have to worry about any View or Window canvas for the rendering process. User has only need to focus on the response and handle it.

Example of use

nef.carbon(code: code,
           style: style,
           outputPath: outputPath,
           success: { completion(true) }, failure: { _ in completion(false) })