Bug 187213 Provid a writer to serialize design in document without any white space.
Add a new writer for serialize design in document without any withe space.
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/writer/IndentableXMLWriter.java
* @param signature
	 *            the unicode signature of the design file
	 * @throws IOException
	 *             if write error occurs
	 */
	public IndentableXMLWriter( OutputStream os, String signature,
			boolean needMarkLineNumber ) throws IOException
	{
		super( os, signature, needMarkLineNumber );
	}
	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.birt.report.model.util.XMLWriter#emitStartTag(java.lang.String)
	 */
	protected IndentableXMLWriter( )
	{
	}
	protected void emitStartTag( String tagName )
	{
		
		lastTagName = tagName;
		literal( getIndent( elementStack.size( ) ) );
		super.emitStartTag( tagName );
	}
	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.birt.report.model.util.XMLWriter#endElement()
	 */