+ * the maximum size that cannot be exceeded (or -1 for
+ * "no maximum") -- if the maximum size would be exceeded by
+ * adding this {@link String}, only a part of it will be added;
+ * if the maximum size is already reached or exceeded (should not
+ * happen because of this method), an empty {@link String} will
+ * be added
+ *
+ * @return the number of characters added (the size of the last
+ * {@link String} in <tt>list</tt>)