Use PDBe by default when opening PDB codes

Previously, the default was to use mmtf format server by RCSB. This format was containing the full connectivity, which is currently missing from bcif files distributed by RCSB.
PDBe distributes "Updated" mmcif files, containing this data. The same content is available in their bcif files.

examples/js/gui.js

@@ -524,7 +524,9 @@ NGL.MenubarFileWidget = function (stage) {
 
   function onPdbInputKeyDown (e) {
     if (e.keyCode === 13) {
-      stage.loadFile('rcsb://' + e.target.value.trim(), {
+      const val = e.target.value.trim()
+      const protocol = val.startsWith('AF_') ? 'rcsb://' : 'pdbe://'
+      stage.loadFile(protocol + val, {
         defaultRepresentation: true
       })
       e.target.value = ''