Add sort options when viewing books

Default view still shows the most recently added books, but adds ability to sort by newest/oldest books and books sorted alphabetically (ascending & descending).

I did not include translations for the next text, but they are split up for easy translating and are otherwise ready for translating.

cps/templates/layout.html

@@ -121,7 +121,19 @@
           <nav class="navigation">
             <ul class="list-unstyled" id="scnd-nav" intent in-standard-append="nav.navigation" in-mobile-after="#main-nav" in-mobile-class="nav navbar-nav">
               <li class="nav-head hidden-xs">{{_('Browse')}}</li>
-              <li id="nav_new"><a href="{{url_for('index')}}"><span class="glyphicon glyphicon-book"></span> {{_('New Books')}}</a></li>
+              <li id="nav_new"><a href="{{url_for('index')}}"><span class="glyphicon glyphicon-book"></span> {{_('Recently Added')}}</a></li>
+              <li class="dropdown">
+                <a href="#" class="dropdown-toggle" data-toggle="dropdown" role="button" aria-haspopup="true" aria-expanded="false">
+                  <span class="glyphicon glyphicon-sort-by-attributes"></span> {{_('Sorted Books')}}
+                  <span class="caret"></span>
+                </a>
+                <ul class="dropdown-menu">
+                  <li><a href="{{url_for('newest_books')}}">{{_('Sort By')}} {{_('Newest')}}</a></li>
+                  <li><a href="{{url_for('oldest_books')}}">{{_('Sort By')}} {{_('Oldest')}}</a></li>
+                  <li><a href="{{url_for('titles_ascending')}}">{{_('Sort By')}} {{_('Title')}} ({{_('Ascending')}})</a></li>
+                  <li><a href="{{url_for('titles_descending')}}">{{_('Sort By')}} {{_('Title')}}  ({{_('Descending')}})</a></li>
+                </ul>
+              </li>
               {% if g.user.show_hot_books() %}
               <li id="nav_hot"><a href="{{url_for('hot_books')}}"><span class="glyphicon glyphicon-fire"></span> {{_('Hot Books')}}</a></li>
               {%endif%}