Bug 40772 [plan item] Smart tab on empty lines
When having the caret on an empty line, pressing tab cleans up the line and sets the caret it the right indentation column.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/ui/PreferenceConstants.java
* <p>
	 * Value is of type <code>Boolean</code>.
	 * </p>
	 *
	 * @since 3.0
	 */	
	public static final String EDITOR_SMART_OPENING_BRACE= "smart_opening_brace"; 
	/**
	 * A named preference that controls if the Java code assist gets auto activated.
	 * <p>
	 * Value is of type <code>Boolean</code>.
	 * </p>
	 */
	public final static String CODEASSIST_AUTOACTIVATION= "content_assist_autoactivation"; 
	/**
	 * A name preference that holds the auto activation delay time in milli seconds.
	 * <p>
	 * Value is of type <code>Int</code>.
	 * </p>
	 */
	public final static String CODEASSIST_AUTOACTIVATION_DELAY= "content_assist_autoactivation_delay"; 
	/**
	 * A named preference that controls if code assist contains only visible proposals.
	 * <p>
	 * Value is of type <code>Boolean</code>. if <code>true<code> code assist only contains visible members. If 
	 * <code>false</code> all members are included.
	 * </p>
	 */
	public final static String CODEASSIST_SHOW_VISIBLE_PROPOSALS= "content_assist_show_visible_proposals"; 
	/**