TypeScript support

[menxit]

Hi, great tool!
I integrated the TypeScript support, let me know if it's ok :)

[vijithassar]

My immediate reaction is that lit-node probably is not the right place to pursue TypeScript support for literate programming. It introduces the project's first dependency, which is very large, requires that dependency even for users who are not using TypeScript, moves away from the relatively simple task of adding loading behaviors to Node, and there isn't a clear line separating TypeScript from other compile-to-JS languages – for example, why not support CoffeeScript as well?

lit.sh was designed to be a language-agnostic solution and may be a better fit for this use case. Or even better, we could lobby for literate programming support in TypeScript directly!