Major refactor to base code + tests

This version includes a major refactor to the base code in which now all native objects and its functions are encapsulated into JS classes. Also, bigint support was added for those values that does not fit in a number. In addition, TypeScript typings were added so you can now use the library in TypeScript, or get fancy recommendations in Visual Studio Code or WebStorm.

A bunch of tests were added as well to test part of the library functionality. During the testing, many bugs were fixed, including one with 24bit audio in Encoder JS classes (which some of the samples were lost). There's room for new tests, but the existing ones are a bit exhaustive.

Nevertheless, new bugs could have been introduced during the refactor, or some olds still be around. If you found one, fill an issue.

Required node version has been changed to 8.x LTS, 10.x LTS or 11, but it is recommended to have 10.x LTS or higher to enable bigint support.

Enjoy :)