abstract_xml_helper: fix preserve_lb=true
abstract_xml_helper: fix preserve_lb=true

by replacing <lb break='no'/> with a "-<br />" when preserve_lb=true.

Otherwise we keep the old functionality around (adding a hyphen with a
span tag).

Fixes: #1445

benwbrum/fromthepage,benwbrum/fromthepage,benwbrum/fromthepage,benwbrum/fromthepage