[relax-ng] Trang, jing update

[James Clark <jjc@jclark.com>]

I've done a new update of jing, trang.  As usual, it's available at:

  http://www.thaiopensource.com/relaxng/

New in this release:

- trang can output the compact syntax

- the compact syntax parser used by jing and trang now matches the compact 
syntax committee spec

- trang XSD output preserves comments

- trang XSD output can take advantage of substitution groups

James