Implement (soft)hyphen handling in Ucto analogues to foliautils

[kosloot]

Some foliautils (like FoLiA-abby and FoliA-tx) will discard soft hyphens (the ¬ symbol) and also 'line terminating' hyphens (also a - at the end of a line). They are replaced by <t-hbr> nodes.
It might be a good extension to ucto to be able to do the same. At least for FoLiA output, but probably for text output too.

Needs some investigation.

This is related to #90 but that discussion was getting messy