add generators and delegated generators benchmarks

[jonathanong]

just found out there's yield* generator which is supposed to be faster - and it is! so i added a benchmark:

now the problem is that if i set the mintime too high, i'll get the following error:

thus, i just made it an environmental variable and set it to 1 millisecond by default. i'm not sure why that happens.

[tj]

hmmm that's not good if we're exhausting stack haha

[tj]

@jonathanong we should add tests for non-thunkable object values as well so stuff like this is ok:

var user = yield {
  name: 'tobi',
  address: get('address')
}

[tj]

maybe it's fine without that, might confuse some people either way

[jonathanong]

Did you want to support that? I think it's a valid use case, but I feel like most future issues will be people trying to do crazy stuff with it. I say add it but don't document it.

[tj]

yeah agreed