Fix sorting of titles that start with 'the'

Because the titles that come from the library data aren't titlecased,
a title like 'The arrest' was being normalised to 'arrest', which sorts
after titles that start with B-Z.  Lowercasing everything makes the sort
more consistent.

assets/library_lookup.js

@@ -171,8 +171,8 @@ function renderBooks() {
     } else if (a.locallyAvailableCopies === 0 & b.locallyAvailableCopies > 0) {
       return 1;
     } else {
-      const sortTitleA = a.title.replace(/^The /, '');
-      const sortTitleB = b.title.replace(/^The /, '');
+      const sortTitleA = a.title.replace(/^The /, '').toLowerCase();
+      const sortTitleB = b.title.replace(/^The /, '').toLowerCase();
 
       return sortTitleA > sortTitleB ? 1 : -1;
     }