Bug 137917 ImageHandle add setFile method.
According to new Resource Deployment Specification, image builder add a new image type 'File', so ImageHandle should add 'setFile' method as other type methods such as 'setURI'.
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/api/ImageHandle.java
* @throws SemanticException
	 *             if the property is locked.
	 */
	public void setHelpText( String helpText ) throws SemanticException
	{
		setStringProperty( ImageItem.HELP_TEXT_PROP, helpText );
	}
	/**
	 * Returns the resource key of the help text of this image item.
	 * 
	 * @return the resource key of the help text
	 */
	public String getHelpTextKey( )
	{
		return getStringProperty( ImageItem.HELP_TEXT_ID_PROP );
	}
	/**
	 * Sets the resource key of help text of this image item.
	 * 
	 * @param helpTextKey
	 *            the help text
	 * 
	 * @throws SemanticException
	 *             if the property is locked.
	 */
	public void setHelpTextKey( String helpTextKey ) throws SemanticException
	{
		setStringProperty( ImageItem.HELP_TEXT_ID_PROP, helpTextKey );
	}
}