Bug 27627: Fix invalid HTMl in OPAC results XSLT: change spans to divs

Bug 27627: Fix invalid HTMl in OPAC results XSLT: change spans to divs

This patch modifies the XSL template for OPAC search results in order to
improve HTML validation: Changing some <span>s to <div>s will prevent an
error when those <span>s contain block-level elements.

To test, apply the patch and restart_all if necessary.

- Confirm that OPACXSLTResultsDisplay is set to "default"
- Perform a catalog search in the OPAC.
- Validate the page source and confirm that there are no errors about
  "Element ul not allowed as child of element span in this context"

Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>