Bug 179674 Support time dimension in model
When define time dimension in model, the "itTime" property will be set. However this is not enough. We also need to know to what precision the time value should be evaluated, say, year, month, day, etc. Model needs to be enhanced to support such requirement.
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/api/olap/LevelHandle.java
*/
	public double getIntervalRange( )
	{
		return this.getFloatProperty( INTERVAL_RANGE_PROP );
	}
	/**
	 * Returns the interval range of this level.
	 * 
	 * @param intervalRange
	 *            the interval range value as a double
	 * @throws SemanticException
	 *             if the property is locked.
	 */
	public void setIntervalRange( double intervalRange )
			throws SemanticException
	{
		setFloatProperty( INTERVAL_RANGE_PROP, intervalRange );
	}
	/**
	 * Sets the interval range of this level.
	 * 
	 * @param intervalRange
	 *            the interval range value as a string.value is locale
	 *            dependent.
	 * @throws SemanticException
	 *             if the property is locked.
	 */
	public void setIntervalRange( String intervalRange )
			throws SemanticException
	{