Fix all existing links and redirection to ?do=login

tpl/default/page.header.html

@@ -60,7 +60,7 @@
           </li>
         {else}
           <li class="pure-menu-item pure-u-lg-0 shaarli-menu-mobile" id="shaarli-menu-mobile-login">
-            <a href="?do=login" class="pure-menu-link">{'Login'|t}</a>
+            <a href="/login" class="pure-menu-link">{'Login'|t}</a>
           </li>
         {/if}
       </ul>
@@ -80,7 +80,7 @@
           </li>
           {if="!$is_logged_in"}
             <li class="pure-menu-item" id="shaarli-menu-desktop-login">
-              <a href="?do=login" class="pure-menu-link"
+              <a href="/login" class="pure-menu-link"
                  data-open-id="header-login-form"
                  id="login-button" aria-label="{'Login'|t}" title="{'Login'|t}">
                 <i class="fa fa-user" aria-hidden="true"></i>

tpl/vintage/page.header.html

@@ -25,7 +25,7 @@
     <li><a href="?do=tools">Tools</a></li>
     <li><a href="?do=addlink">Add link</a></li>
     {else}
-    <li><a href="?do=login">Login</a></li>
+    <li><a href="/login">Login</a></li>
     {/if}
     <li><a href="{$feedurl}?do=rss{$searchcrits}" class="nomobile">RSS Feed</a></li>
     {if="$showatom"}