client/general: add < > vim navigation hints

For example, in Vimperator, one now can navigate to previous/next page
or post by pressing f< or f>.

client/css/pager.styl

@@ -4,13 +4,6 @@
     nav
         .disabled
             opacity: .5
-        .prev span,
-        .next span
-            opacity: 0
-            position: absolute
-            display: block
-            width: 0
-            height: 0
 
     .page
         position: relative

client/html/manual_pager_nav.tpl

@@ -7,7 +7,7 @@
                 <a class='prev disabled'>
             <% } %>
                 <i class='fa fa-chevron-left'></i>
-                <span>Previous page</span>
+                <span class='vim-nav-hint'>&lt; Previous page</span>
             </a>
         </li>
 
@@ -32,7 +32,7 @@
                 <a class='next disabled'>
             <% } %>
                 <i class='fa fa-chevron-right'></i>
-                <span>Next page</span>
+                <span class='vim-nav-hint'>Next page &gt;</span>
             </a>
         </li>
     </ul>

client/html/post.tpl

@@ -12,7 +12,7 @@
                     <a class='inactive'>
                 <% } %>
                     <i class='fa fa-chevron-left'></i>
-                    <span class='vim-nav-hint'>Next post</span>
+                    <span class='vim-nav-hint'>&lt; Next post</span>
                 </a>
             </article>
             <article class='previous-post'>
@@ -26,7 +26,7 @@
                     <a class='inactive'>
                 <% } %>
                     <i class='fa fa-chevron-right'></i>
-                    <span class='vim-nav-hint'>Previous post</span>
+                    <span class='vim-nav-hint'>Previous post &gt;</span>
                 </a>
             </article>
             <article class='edit-post'>