add utility date formatting functions

xwords4/android/XWords4/src/org/eehouse/android/xw4/DbgUtils.java

@@ -145,6 +145,18 @@ public class DbgUtils {
         }
     }
 
+    public static String secondsToDateStr( long seconds )
+    {
+        return millisToDateStr( seconds * 1000 );
+    }
+
+    public static String millisToDateStr( long millis )
+    {
+        Time tim = new Time();
+        tim.set( millis );
+        return tim.format2445();
+    }
+
     // public static String toString( long[] longs )
     // {
     //     String[] asStrs = new String[longs.length];