Combine conflict callback API messages differing only by punctuation

* subversion/libsvn_wc/conflicts.c
  (generate_propconflict, resolve_text_conflicts): Combine messages
   which differ only by punctuation, remove trailing period from another


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1435268 13f79535-47bb-0310-9956-ffa450edef68