Call of hook_fieldgroup_view doesn't permit group or element update

This is an extremely easy fix.

Because $element and $group aren't passed in by reference in the following, hook_fieldgroup_view doesn't accomplish anything.

Current code (lines 569-572):

          foreach (module_implements('fieldgroup_view') as $module) {
            $function = $module .'_fieldgroup_view';
            $function($node, $element, $group, $context);
          }

Note that I'm not sure if $group needs to be passed by reference. (???) Nevertheless, if that last line is changed to

            $function($node, &$element, &$group, $context);

then things I do in my hook_fieldgroup_view function actually have an effect.