Bug 132786 Value2 should be cleaned after convert operator from between to equal in highlight rule.
Description: Value2 should be cleaned after convert operator from between to equal in highlight rule. Steps to reproduce: 1. Insert a data. 2. Set highlight rule in Property Editor. 2 between 1 and 3, color blue. 3. Save the report 4. Modify highlight rule, change to 1 equal 1, color blue. 5. Save the report, see generated xml source. Expected result: In xml source, value2 should be cleaned in highlight expression. Actual result: In xml source, value1 is 1 and value2 is 3.
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/api/HighlightRuleHandle.java
* Returns a dimension handle for a member.
	 * 
	 * @param memberName
	 *            the member name.
	 * @return A DimensionHandle for the given member.
	 */
	private DimensionHandle doGetDimensionHandle( String memberName )
	{
		MemberRef memberRef = new CachedMemberRef( structRef, memberName );
		return new DimensionHandle( getElementHandle( ), memberRef );
	}
	/**
	 * Returns the font family handle of the highlight rule.
	 * 
	 * @return the font family handle of the highlight rule.
	 */
	public FontHandle getFontFamilyHandle( )
	{
		MemberRef memberRef = new CachedMemberRef( structRef,
				HighlightRule.FONT_FAMILY_MEMBER );
		return new FontHandle( getElementHandle( ), memberRef );
	}
	/**
	 * Returns the font weight of the highlight rule. The return value is
	 * defined in <code>DesignChoiceConstants</code> and can be one of:
	 * <ul>
	 * <li><code>FONT_WEIGHT_NORMAL</code>
	 * <li><code>FONT_WEIGHT_BOLD</code>
	 * <li><code>FONT_WEIGHT_BOLDER</code>
	 * <li><code>FONT_WEIGHT_LIGHTER</code>