add importing folders as modules

[michaelbull]

https://github.com/basarat/typescript-book/blob/master/docs/tips/barrel.md

Perhaps this will be useful? Seems like a good document to reference and that a "barrel" is the common name for this pattern.

[gerbendekker]

Nice, its looks like I have learned something today!

[Alexander-Taran]

Thanks for your contribution (-: Keep 'em coming