update wikiFN with third paramter, $clean

value defaults to true

patch also includes an update to idx_parseIndexLine to make use of the
new parameter - the index file (if built by DokuWiki's methods) will
contain already "clean" IDs.

darcs-hash:20060825144112-9b6ab-55adc71cf55bb58468fb3f0b03b9001ab149a82b.gz