Fix #1674 -- Change spelling of e-mail to email (#4636)

* Fix #1674 -- Change spelling of e-mail to email

* Conflicts and word list

* Add MobilePay to wordlist

* fix usage in tests

src/pretix/control/templates/pretixcontrol/order/sendmail.html

@@ -24,7 +24,7 @@
             {% endif %}
             {% if request.method == "POST" %}
                 <fieldset>
-                    <legend>{% trans "E-mail preview" %}</legend>
+                    <legend>{% trans "Email preview" %}</legend>
                     <div class="tab-pane mail-preview-group">
                         <div lang="{{ order.locale }}" class="mail-preview">
                             <strong>{{ preview_output.subject }}</strong><br><br>