Bug 181121 Model should provide utility method for cube to get correspond dimension key.
In model cube handle, the relation of cube data set and dimension data sets are managed by a series of dimension condition handles.We need model to add utility method so that we can easily get corresponding dimension data set column names according to given cube dimension keys.
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/core/Structure.java
PropertyDefn prop = (PropertyDefn) getDefn( ).getMember( memberName );
		if ( prop == null )
			return null;
		return getLocalProperty( module, prop );
	}
	/**
	 * Sets the value of the member.
	 * 
	 * @param propName
	 *            the member name to set
	 * @param value
	 *            the value to set
	 */
	public final void setProperty( String propName, Object value )
	{
		PropertyDefn prop = (PropertyDefn) getDefn( ).getMember( propName );
		if ( prop == null )
			return;
		setProperty( prop, value );
	}
	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.birt.report.model.core.IPropertySet#setProperty(org.eclipse.birt.report.model.metadata.PropertyDefn,
	 *      java.lang.Object)
	 */
	public void setProperty( PropertyDefn prop, Object value )
	{
		updateReference( prop, value );
		if ( prop.isIntrinsic( ) )