Add ByteString.Lazy utilities

[berewt]

The starting point was a similar issue from the one raised in #209. Compared to the solution proposed in the thread, I'd prefer to go for a whole set of utilities for ByteString.Lazy. It allows almost the same shell facilities than the strict version, except that chunks are meaningless here.

[Gabriella439]

Wow, thanks for doing this! Give me a day or two to review this more closely, but I approve of the overall direction of this

[berewt]

Regarding the signature changes: yep, I forgot to transitively generalise the functions that depends on inhandle, thanks.

Regarding the stream / streamWithErr, maybe I should only keep the strict version and rename them as stream and streamWithErr, as the strict names can be misleading, what do you think about it?

[Gabriella439]

Yeah, I agree that they don't need the strict in the names for this module

[berewt]

One more question then, if we remove stream / streamWithError in favour of systemStrict / systemStrictWithError, what do we do with function like inProc, that was previously relying on stream, and will now use systemStrict:

1. keep their signature as is and discard the ExitCode;
2. change them, to include the ExitCode?

[Gabriella439]

I think you don't even inproc any longer since proc and the new stream utility supersede it

Or you could rename the new stream utility to inproc instead for conceptual consistency

[berewt]

I finally decided to drop the in* function and went for a *Stream name instead. The names are consistent with the *Strict equivalent in Turtle.ByteString. Please do not hesitate to propose something else if you're not happy with the result, I'm not totally satisfied myself either. ;-)