WIP: Generators proof of concept

[Steveb-p]

Purpose of this PR is to introduce generators, maintaining backward compatibility with current usage expecting Promises if possible.

At the time of initial PR, it simply creates a generator function which is immediately wrapped around with promisify-generator and does not really change the behaviour, slightly increasing memory footprint.

To maintain compatibility with node 6.x code will probably need to be transpiled via babel.

[AlexZeitler]

Will look into it later this evening

[AlexZeitler]

Speaking of transpiling: I was already thinking about refactoring the source towards TypeScript - what do think about that?

[Steveb-p]

Speaking of transpiling: I was already thinking about refactoring the source towards TypeScript - what do think about that?

I don't mind, though I'm not well versed in TypeScript specifics. But there doesn't seem much code that uses advanced TypeScript here and we can always migrate incrementally I guess.

[frank-dspeed]

i have a Already working Implamentation of a docker-compose interactive version that uses most streams it allows to run interactive sessions as also supports log follow and other stuff

it is also implamented as a class so that you don't need to always set cwd and that @Steveb-p @AlexZeitler

[Steveb-p]

I'll rewrite this completely.

[AlexZeitler]

@Steveb-p Looking forward to it!