Payments add modal form

* adds modal form for adding payments
* generalizes generic_table_form.html for table-form-like usage in modal_form.html
* adds css enhancements for focused input fields
* adds BaseModalForm as specification to BaseForm, which inherits the BSModalForm class as well
* adds translations

templates/table/generic_table_form.html

@@ -0,0 +1,36 @@
+{% load i18n  %}
+
+{% block head %}
+    {{ form.media }}
+{% endblock %}
+
+{% block body %}
+<div class="container">
+    <h4>
+        {{ form.form_title }}
+    </h4>
+    {% if form.form_caption is not None %}
+    <small>
+        {{ form.form_caption }}
+    </small>
+    {% endif %}
+    <form method="post" action="{{ form.action_url }}">
+        {% csrf_token %}
+        {% include 'table/generic_table_form_body.html' %}
+        <div class="row">
+            <div class="col-md">
+                <a href="{{ form.cancel_redirect }}">
+                    <button class="btn btn-default" type="button" title="{% trans 'Cancel' %}">{% trans 'Cancel' %}</button>
+                </a>
+            </div>
+            <div class="col-md d-flex justify-content-end">
+                <button class="btn btn-default" type="submit" title="{% trans 'Save' %}">{% trans 'Save' %}</button>
+            </div>
+        </div>
+    </form>
+</div>
+{% endblock %}
+
+{% block footer %}
+    {{ form.media }}
+{% endblock %}

templates/table/generic_table_form_body.html

@@ -0,0 +1,20 @@
+{% load i18n %}
+        <table class="table">
+            <tbody>
+                {% for field in form %}
+                <tr title="{{ field.help_text }}" class="{% if field.errors %}error{% endif %}">
+                    <th scope="row" class="col-sm-3">
+                        <div>{{ field.label }}<span class="label-required">{% if field.field.required %}*{% endif %}</span></div>
+                        <small>{{ field.help_text }}</small>
+                    </th>
+                    <td class="col-sm-9">
+                        {{ field }}
+                        {% for error in field.errors %}
+                        <strong>{{ error }}</strong>
+                        {% endfor %}
+                    </td>
+                </tr>
+                {% endfor %}
+            </tbody>
+        </table>
+        <small>{% trans 'Fields with * are required.' %}</small>