Disallow empty titles (#5785) (#5794)

* add util method and tests

* make sure the title of an issue cannot be empty

* wiki title cannot be empty

* pull request title cannot be empty

* update to make use of the new util methof

options/locale/locale_en-US.ini

@@ -655,6 +655,7 @@ ext_issues.desc = Link to an external issue tracker.
 
 issues.desc = Organize bug reports, tasks and milestones.
 issues.new = New Issue
+issues.new.title_empty = Title cannot be empty
 issues.new.labels = Labels
 issues.new.no_label = No Label
 issues.new.clear_labels = Clear labels