Item12904: work around different styles of inconsistencies in renderForDisplay across foswiki core engines

also:
- reworked delete handler
- implemented save handlers for meta data
- fixed table markup to pleae Foswiki:Extensions:JQDataTablesPlugin 



git-svn-id: http://svn.foswiki.org/trunk/MetaDataPlugin@17675 0b4bb1d4-4e5a-0410-9cc4-b2b747904278