events: allow editing of all used values

Allow to change the date/time and
other relevant values of an event
on creation and after it was created.

app/src/main/res/layout/temperature_dialog.xml

@@ -23,4 +23,12 @@
         android:layout_height="wrap_content"
         android:textSize="30sp"
         android:textColor="@color/accent"/>
+
+    <TextView
+        android:id="@+id/dialog_date_picker"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:layout_gravity="center"
+        android:layout_marginEnd="20dp"/>
+
 </LinearLayout>