Added option to switch themes.

Added standalone pages for:
 - Exhibitions
 - Events
 - Institutions
 - Collections
Added option to limit display to only a given set of institutions.

edit/themes/default/default.css

@@ -109,6 +109,8 @@ table.obj_cha_maintable button:only-child,
 table.obj_cha_maintable input:only-child    { width: 100%; }
 table.obj_cha_maintable textarea:only-child { width: 100%; height: 14em; }
 
+table.obj_cha_maintable input[type="range"]:only-child { margin: .5em -1em 0 0; }
+
 @media screen and (min-width:65em) {
     table.obj_cha_maintable th { width: 16em; }
 }