Support ES6 module import

[atiris]

ES6 named module import is not possible for this library.
Check why this is not possible:

import { Gomshal } from 'gomshal';

Error:

import { Gomshal } from 'gomshal';
         ^^^^^^^
SyntaxError: The requested module 'gomshal' does not provide an export named 'Gomshal'
  at ModuleJob._instantiate (internal/modules/esm/module_job.js:92:21)
  at async ModuleJob.run (internal/modules/esm/module_job.js:107:20)
  at async Loader.import (internal/modules/esm/loader.js:164:24)