Redirect to the page you came from after logging in

turns out this is already a feature of the login page, we just needed to
make use of it

Also made sure to not redirect to /users/logout

project/thscoreboard/thscoreboard/templates/base.html

@@ -40,7 +40,7 @@
                 {% endif %}
                 {% else %}
                 <div class="banner-link">
-                    <a href="/users/login">{% translate 'Log in' context 'Top bar' %}</a>
+                    <a href="/users/login{% if request.path != "/users/logout" %}?next={{request.path}}{% endif %}">{% translate 'Log in' context 'Top bar' %}</a>
                 </div>
                 <div class="banner-link">
                     <a href="/users/register">{% translate 'Sign Up' context 'Top bar' %}</a>