Display errors on invalid forms

It will probably need a bit of styling…

templates/session/login.html.tera

@@ -10,11 +10,8 @@
 <p>{{ message }}</p>
 {% endif %}
 <form method="post">
-    <label for="email_or_name">{{ "Username or email" | _ }}</label>
-    <input type="text" id="email_or_name" name="email_or_name" />
-
-    <label for="password">{{ "Password" | _ }}</label>
-    <input type="password" id="password" name="password" />
+    {{ macros::input(name="email_or_name", label="Username or email", errors=errors, form=form) }}
+    {{ macros::input(name="password", label="Password", errors=errors, form=form, type="password") }}
 
     <input type="submit" value="{{ "Login" | _ }}" />
 </form>