Merge branch 'ot/libify-get-ref-atom-value'

Code restructuring, in preparation for further work. * ot/libify-get-ref-atom-value: ref-filter: libify get_ref_atom_value() ref-filter: add return value to parsers ref-filter: change parsing function error handling ref-filter: add return value && strbuf to handlers ref-filter: start adding strbufs with errors ref-filter: add shortcut to work with strbufs