Bug 7489 - Implement DisplayOPACiconsXSLT for NORMARC XSLT

Bug 7489 - Implement DisplayOPACiconsXSLT for NORMARC XSLT

This patch actually hides the whole line that contains the icon in the result
list, including "literary form" and "audience", but this is how the syspref
works for MARC21 too, so I'm sticking with that.

To test:
- Set marcflavour = NORMARC
- Set OPACXSLTResultsDisplay = on
- Set DisplayOPACiconsXSLT = show
- Check that icons and information about "Type", "Litterær form" and
  "Målgruppe" are displayed in results, "Type" and the icon in detail
- Set DisplayOPACiconsXSLT = don't show
- Check that icons and information is not displayed in result or detail

Signed-off-by: Katrin Fischer <Katrin.Fischer.83@web.de>
Test plan worked nicely. Patch works as advertised.

Signed-off-by: Paul Poulain <paul.poulain@biblibre.com>