Bug 188578 Add "displayColumnName" on TabularLevel
Add Property "displayColumnName" on TabbularLevel and corresponding APIs on handle. Property Type: expression.
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/writer/ModuleWriter.java
{
	/**
	 * The low-level writer that emits XML syntax.
	 */
	/**
	 * The constant for default model name space.
	 */
	final protected static String DEFAULT_NAME_SPACE = "http:www.eclipse.org/birt/2005/design"; 
	/**
	 * The XML writer.