thesaurus is finally working... It contains recursive entries to parnet

thesaurus is finally working... It contains recursive entries to parnet
term, and we actually needed to display narrower terms, so mem_lookup was
created. Important changes:
- you can write eval{"901a" eq "Mikrotezaurus"} within <isis>
  tag and if expression evaluates to false, no content will be outputed
  (It's used to hide microtesarus terms from lover level descriptors)
- mem_lookup.pm now supports formats: you can write something like
  [a:5614];;[d:[a:5614]] and it will correctly embed values

git-svn-id: file:///home/dpavlin/private/svn/webpac/branches/hidra@207 13eb9ef6-21d5-0310-b721-a9d68796d827