Line breaking in discourse vis based on annotations

[amir-zeldes]

It should be possible to get line breaks in the discourse visualization based on the beginning of an annotation. This could be configured via mappings. For example, if there is an annotation p="p", which stands for paragraphs in the original document, we could use the mapping:

break:p="p"

to tell the discourse visualizer to start a new line of tokens as soon as the first token on the left border of an annotation p="p" occurs. It should be possible to map multiple breaking elements (e.g. pb and lb for page break and line break, both cause a line break in the vis), and it should be possible to condition with or without the annotation value, e.g.

break:p="p",lb,pb

This should cause a line break every time an annotation 'lb' or 'pb' begins, and also for 'p', but only if the value is also "p" (for lb and pb the value has been left open).

[thomaskrause]

also see #80 for a more general concept