Added button to remove all attachments

app/src/main/java/eu/faircode/email/DaoAttachment.java

@@ -157,6 +157,10 @@ public interface DaoAttachment {
             " WHERE id = :id")
     int deleteAttachment(long id);
 
+    @Query("DELETE FROM attachment" +
+            " WHERE message = :message")
+    int deleteAttachments(long message);
+
     @Query("DELETE FROM attachment" +
             " WHERE message = :message" +
             " AND (encryption IS NULL OR encryption NOT IN (:keep))")