[fix] templates: remove unneeded escape \' of single quotation mark

Strings like::

    'Query in the page\'s title'

are hard to read / remove escape sequence by using double quotation marks for
strings ::

    "Query in the page's title"

BTW: remove a leading dot in the simple theme [1].

[1] 80fb77476f (r756112716)

Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>

searx/templates/simple/messages/no_results.html

@@ -18,6 +18,6 @@
 {% else %}
 <div class="dialog-error" role="alert">
   <p><strong>{{ _('Sorry!') }}</strong></p>
-  <p>{{ _('we didn\'t find any results. Please use another query or search in more categories.') }}</p>
+  <p>{{ _("we didn't find any results. Please use another query or search in more categories.") }}</p>
 </div>
 {% endif %}