updated hanging-punctuation (no change, only spec link) per https://www.w3.org/TR/2018/WD-css-text-3-20181212/#hanging-punctuation-property

This is the final update for css-text-3 updates, so it fixes #220

Author: ylafon

org/w3c/css/properties/css3/CssHangingPunctuation.java

@@ -1,7 +1,7 @@
 //
 // Author: Yves Lafon <ylafon@w3.org>
 //
-// (c) COPYRIGHT MIT, ERCIM and Keio University, 2012.
+// (c) COPYRIGHT MIT, ERCIM, Keio University, Beihang, 2012.
 // Please first read the full copyright statement in file COPYRIGHT.html
 package org.w3c.css.properties.css3;
 
@@ -17,7 +17,7 @@
 import java.util.ArrayList;
 
 /**
- * @spec https://www.w3.org/TR/2017/WD-css-text-3-20170822/#hanging-punctuation-property
+ * @spec https://www.w3.org/TR/2018/WD-css-text-3-20181212/#propdef-hanging-punctuation
  */
 public class CssHangingPunctuation extends org.w3c.css.properties.css.CssHangingPunctuation {