Multiline texts are not supported yet

[thoughteer]

We need a mechanism for multiline text translation.

We can just split text node contents by the new line symbol and try to translate lines separately. In this case we can still rely on the TSV format for the dictionary.

[thoughteer]

We can rely on hidden line/paragraph separator symbols. In this case we can keep the TSV format. But the content normalization procedure should be reimplemented.