Add a new parser that does not buffer lines

[riquito]

We do already stream data, with a caveat: we keep each line in memory. If a single line were to exceed the amount of memory we can allocate, tuc would crash (and before that happens your computer wouldn't be too happy).

In some scenarios we can use a pure streaming algorithm that does not buffer lines. Among other things that we can't support when we use the streaming alg is that we won't support negative indices for fields (because that require to read the line first). Other options too won't be available. As for "fast lane", we will use this route only if the options provided by the user allows it.