Bug 126414 [Commands] handlers: Provide help context ids
For commands and handlers to replace actions, they need to be capable of providing help context identifiers. For an example, see OpenResourceHandler in org.eclipse.ui.ide. This help context id will need to be definable through XML and through code.
bundles/org.eclipse.core.commands/src/org/eclipse/core/commands/CommandManager.java
* <code>serializedParameterizedCommand</code> does not exist in the
	 * encoded command, that parameter id and value are ignored. A given
	 * parameter id should not be used more than once in
	 * <code>serializedParameterizedCommand</code>. This will not result in
	 * an exception, but in this case the value of the parameter when the
	 * command is executed is unspecified.
	 * </p>
	 * <p>
	 * This method will never return <code>null</code>, however it may throw
	 * an exception if there is a problem processing the serialization string or
	 * the encoded command is undefined.
	 * </p>
	 * 
	 * @param serializedParameterizedCommand
	 *            a string representing a command id and parameter ids and
	 *            values; must not be <code>null</code>
	 * @return a {@link ParameterizedCommand} with the command and
	 *         parameterizations encoded in the
	 *         <code>serializedParameterizedCommand</code>; never
	 *         <code>null</code>.
	 * @throws NotDefinedException
	 *             if the command indicated in
	 *             <code>serializedParameterizedCommand</code> is not defined
	 * @throws SerializationException
	 *             if there is an error deserializing
	 *             <code>serializedParameterizedCommand</code>
	 * @see ParameterizedCommand#serialize()
	 * @since 3.2
	 */
	public final ParameterizedCommand deserialize(