amendments to previous patch updating rss & cache

rss syntax extended to include a refresh parameter
 <digits><period>  period can be d,h,m for days, hours, minutes respectively
                   if not specified will default to 4 hours
                   dokuwiki imposes a minimum of 10 minutes

metadata now used "date valid age" (seconds) rather than "date valid end"

darcs-hash:20060925201222-9b6ab-c8e6d8e40bb178295bab874fce5147ccff35fbbb.gz