a fix (at least for now) for issue 0002994

• core/string_api.php
  (string_process_bug_link): loosen our bug tag matching rules to allow
  matches whenever the bug tag comes after a non-word character (\W in
  regular expressions) instead of only after whitesapce. This may be too
  loose, but we will see.

git-svn-id: http://mantisbt.svn.sourceforge.net/svnroot/mantisbt/trunk@2008 <a class="text" href="/?p=mantisbt.git;a=object;h=f5dc347c">f5dc347c</a>-c33d-0410-90a0-b07cc1902cb9