Add list of 'parent' tickets to ticket description table

'parent' tickets are all tickets on which the current ticket depends.

The parent tickets can only be resolved if the current tickets is closed.

This patch splits the current |Dependencies|Total time spent| table row
in two rows.  The table layout is now

    |Status |Total time spent|
    |Depends|Resolves        |

Status and Total time only have one line.  Status was chosen as filler
field, because I believe it should be moved out of the title to reduce
visual distraction.

Depends and Resolve will have a variable number of lines and are closely
related.

Depends was chosen instead of "Dependencies", to indicate directly what
the listed tickets do and because it is shorter.

The commit also simplifies the wording of the tooltips and harmonizes with
the other tooltips in the same table: It indicates directly what happens
when the button is clicked (or touched!).

Notes:

- The complete row could be omitted if now Depends or Resolves exists for
  a ticket.  This would reduce visual distraction but was not implemented
  because it could lead to misled expectations.
- No button for removing/adding parent tickets was added. If considered
  important this can be added any time.  Currently a user has to go to
  the parent ticket and delete the dependency (easy) or remember the ticket
  id/title, search for the parent and add the ticket as dependency (difficult)

helpdesk/templates/helpdesk/ticket_desc_table.html

@@ -117,24 +117,9 @@
                         </td>
                     </tr>
 
-                    {% if helpdesk_settings.HELPDESK_ENABLE_DEPENDENCIES_ON_TICKET != False and helpdesk_settings.HELPDESK_ENABLE_TIME_SPENT_ON_TICKET != False %}
+		    <tr>
-                        <tr>
+			<th class="table-active">{% trans "Status" %}</th>
-                            {% if helpdesk_settings.HELPDESK_ENABLE_DEPENDENCIES_ON_TICKET %}
+			<td>{{ ticket.get_status }}</td>
-                                <th class="table-active">{% trans "Dependencies" %}</th>
-                                <td>
-                                    <a data-toggle='tooltip' href='{% url 'helpdesk:ticket_dependency_add' ticket.id %}' title="{% trans "Click on 'Add Dependency', if you want to make this ticket dependent on another ticket. A ticket may not be closed until all tickets it depends on are closed." %}"><button type="button" class="btn btn-primary btn-sm float-right"><i class="fas fa-link"></i></button></a>
-                                    {% for dep in ticket.ticketdependency.all %}
-                                    {% if forloop.first %}<p>{% trans "This ticket cannot be resolved until the following ticket(s) are resolved" %}</p><ul>{% endif %}
-                                        <li><a href='{{ dep.depends_on.get_absolute_url }}'>{{ dep.depends_on.ticket }} {{ dep.depends_on.title }}</a> ({{ dep.depends_on.get_status_display }}) <a href='{% url 'helpdesk:ticket_dependency_del' ticket.id dep.id %}'><button type="button" class="btn btn-warning btn-sm"><i class="fas fa-trash"></i></button></a></li>
-                                        {% if forloop.last %}</ul>{% endif %}
-                                    {% empty %}
-                                    {% trans "This ticket has no dependencies." %}
-                                    {% endfor %}
-                                </td>
-                            {% else %}
-                                <th class="table-active"></th>
-                                <td></td>
-                            {% endif %}
                             {% if helpdesk_settings.HELPDESK_ENABLE_TIME_SPENT_ON_TICKET %}
                                 <th class="table-active">{% trans "Total time spent" %}</th>
                                 <td>{{ ticket.time_spent_formated }}</td>
@@ -142,8 +127,41 @@
                                 <th class="table-active"></th>
                                 <td></td>
                             {% endif %}
-                        </tr>
+		    </tr>
-                    {% endif %}
+                    {% if helpdesk_settings.HELPDESK_ENABLE_DEPENDENCIES_ON_TICKET != False %}
+		    <tr>
+                        <th class="table-active">{% trans "Depends" %}</th>
+                        <td>
+                            <a data-toggle='tooltip' href='{% url 'helpdesk:ticket_dependency_add' ticket.id %}'
+			       title='{% trans "Make this ticket dependent on another ticket. A ticket may not be closed until all tickets it depends on are closed or removed." %}'>
+				<button type="button" class="btn btn-primary btn-sm float-right"><i class="fas fa-link"></i></button></a>
+                            {% for dep in ticket.ticketdependency.all %}
+			    {% if forloop.first %}<ul>{% endif %}
+				<li>
+				    <a href='{{ dep.depends_on.get_absolute_url }}'>{{ dep.depends_on.ticket }} {{ dep.depends_on.title }}</a>
+				    ({{ dep.depends_on.get_status_display }})
+				    <a data-toggle='tooltip' href='{% url 'helpdesk:ticket_dependency_del' ticket.id dep.id %}'
+				       title='{% trans "Drop the dependency on this ticket. A ticket may not be closed until all tickets it depends on are closed or removed." %}'>
+					<button type="button" class="btn btn-warning btn-sm"><i class="fas fa-trash"></i></button></a></li>
+                                {% if forloop.last %}</ul>{% endif %}
+                            {% empty %}
+                            {% trans "This ticket has no dependencies." %}
+                            {% endfor %}
+                        </td>
+			<th class="table-active">{% trans "Resolves" %}</th>
+			<td>
+			    {% for parent in ticket.depends_on.all %}
+			    {% if forloop.first %}<ul>{% endif %}
+				<li>
+				    <a href='{{ parent.ticket.get_absolute_url }}'>{{ parent.ticket.ticket }} {{ parent.ticket.title }}</a>
+				</li>
+				{% if forloop.last %}</ul>{% endif %}
+			    {% empty %}
+			    {% trans "This ticket does not resolve any other" %}
+			    {% endfor %}
+			</td>
+		    </tr>
+		    {% endif %}
                     {% if ticket.kbitem %}
                         <tr>
                             <th class="table-active">{% trans "Knowlegebase item" %}</th>