Add a button to set links as sticky

Meaning that they always appear on top of all links

Fixes #186

tpl/default/linklist.html

@@ -201,6 +201,12 @@
                         <i class="fa fa-trash"></i>
                       </a>
                     </span>
+                    <span class="linklist-item-infos-controls-item ctrl-pin">
+                      <a href="?do=pin&amp;id={$value.id}&amp;token={$token}"
+                         title="{$strDelete}" class="pin-link {if="$value.sticky"}pinned-link{/if} pure-u-0 pure-u-lg-visible">
+                        <i class="fa fa-thumb-tack"></i>
+                      </a>
+                    </span>
                   </div>
                 {/if}
                 <a href="?{$value.shorturl}" title="{$strPermalink}">