Bug 24084: PlainMARC view broken on OPAC if other $.ajax calls produce errors

Bug 24084: PlainMARC view broken on OPAC if other $.ajax calls produce errors

This patch removes the use of jQuery's ajaxSetup() and load() to get the
"plain" MARC view and replaces it with $.get(). This allows for
error-handling on this specific AJAX request rather than all on the
page.

To test, apply the patch and view a bibliographic record in the OPAC.

 - Click the "MARC view" tab.
 - Click the "view plain" link.
  - The plain-text MARC view should load.
  - Clicking "view labeled" should return you to the original view.

To test error handling, edit opac-MARCdetail.tt line 185 and add a typo
to the URL, e.g. "opac-showmark.pl." Repeat the above steps. Clicking
the "view plain" link should trigger an error message: "Sorry, plain
view is temporarily unavailable."

Signed-off-by: Lucas Gass <lucas@bywatersolutions.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>