Prevent display of hidden metadata fields in slideshow

On 2007-08-01 Colin Eliott of Athabasca University pointed out that hidden metadata fields were displayed by the metadata viewer of the slideshow viewer (inside favorite).

The associated web template is fav_meta_viewer.php. I have no idea why fav_meta_viewer.php doesn't just call meta_scr.php, but I attribute it to the general inconsistency and disarray of the CONTENTdm code base. In any case meta_scr.php is quite complex, so i'm not going to call it either.

Instead apply the following patch.

This just checks that the field is not hidden before displaying it.