better support for case_exact search (not caseexact for consistency),

better support for case_exact search (not caseexact for consistency),
plugin args simplification:
  handle and explode exclude and pages argument in WikiPlugin::getArgs
    and exclude in advance (at the sql level if possible)
  handle sortby and limit from request override in WikiPlugin::getArgs
ListSubpages: renamed pages to maxpages

git-svn-id: svn://svn.code.sf.net/p/phpwiki/code/trunk@4167 96ab9672-09ca-45d6-a79d-3d69d39ca109