A DuffPane is now a TibetanPane. A TibetanPane is much more lightweight

but does line breaks correctly.  I.e., I refactored DuffPane into two classes.

I did this trying to track down a subtle bug in line breaking: 'gye ' breaks
after 'gy' sometimes, with the dreng bo on the next line, but only when you
resize the window certain ways, and only in Savant (and maybe QD and the
translation tool, I don't know) but not in Jskad.

I was not successful in finding the bug, but it still exists when I use
TibetanPanes instead of DuffPanes in org.thdl.savant.tib.*.

source/org/thdl/tib/text/TibetanDocument.java

@@ -35,8 +35,8 @@ import org.thdl.util.ThdlDebug;
 public class TibetanDocument extends DefaultStyledDocument {
 	private int tibetanFontSize = 36;
 
-    /** Do not use this contructor. */
-    private TibetanDocument() { super(); }
+    /** Creates a new TibetanDocument with default styles. */
+    public TibetanDocument() { super(); }
 
     /** Do not use this contructor. */
     private TibetanDocument(AbstractDocument.Content c, StyleContext styles ) {