Merge branch 'hv/ref-filter-misc'

The "--format=" option to the "for-each-ref" command and friends learned a few more tricks, e.g. the ":short" suffix that applies to "objectname" now also can be used for "parent", "tree", etc. * hv/ref-filter-misc: ref-filter: add `sanitize` option for 'subject' atom pretty: refactor `format_sanitized_subject()` ref-filter: add `short` modifier to 'parent' atom ref-filter: add `short` modifier to 'tree' atom ref-filter: rename `objectname` related functions and fields ref-filter: modify error messages in `grab_objectname()` ref-filter: refactor `grab_objectname()` ref-filter: support different email formats