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
/**
	 * Sets a table of contents entry for this item. The TOC property defines an
	 * expression that returns a string that is to appear in the Table of
	 * Contents for this item or its container.
	 * 
	 * @param expression
	 *            the expression that returns a string
	 * @throws ScriptException
	 *             if the TOC property is locked by the property mask.
	 * 
	 * @see #getTocExpression()
	 */
	void setTocExpression( String expression ) throws ScriptException;
	/**
	 * Return the sort type.
	 * 
	 * @return the sort type.
	 */
	String getSortType( );
	/**
	 * Sets the sort type, which indicates the way of sorting
	 * 
	 * @param sortType
	 *            sort type.
	 * @throws ScriptException
	 *             if the property is locked.
	 */
	void setSortType( String sortType ) throws ScriptException;
}