Bug 168172 Add the get() and set() functions of HideDetail parameter on IGroup
Add the get() and set() functions of HideDetail parameter on IGroup, and thus enable the hidedetail shifting on the Group through eventhandler.
engine/org.eclipse.birt.report.engine/src/org/eclipse/birt/report/engine/api/script/element/IGroup.java
* @param intervalRange
	 *            the interval range value as a double
	 * @throws ScriptException
	 *             if the property is locked.
	 */
	void setIntervalRange( double intervalRange ) throws ScriptException;
	/**
	 * Returns the sort direction of this group. The return value is defined in
	 * <code>DesignChoiceConstants</code> and can be one of:
	 * 
	 * <ul>
	 * <li><code>SORT_DIRECTION_ASC</code>
	 * <li><code>SORT_DIRECTION_DESC</code>
	 * 
	 * </ul>
	 * 
	 * @return the sort direction of this group
	 */
	String getSortDirection( );
	/**
	 * Sets the sort direction of this group. The return value is defined in
	 * <code>DesignChoiceConstants</code> and can be one of:
	 * 
	 * <ul>
	 * <li><code>SORT_DIRECTION_ASC</code>
	 * <li><code>SORT_DIRECTION_DESC</code>
	 * 
	 * </ul>
	 * 
	 * @param direction