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/Command.java
*            <code>null</code>.
	 * @since 3.2
	 */
	private final void fireNotEnabled(final NotEnabledException e) {
		
		if (DEBUG_COMMAND_EXECUTION) {
			Tracing.printTrace("COMMANDS", "execute" + Tracing.SEPARATOR 
					+ "not enabled: id=" + getId() + "; exception=" + e); 
		}
		if (executionListeners != null) {
			final Object[] listeners = executionListeners.getListeners();
			for (int i = 0; i < listeners.length; i++) {
				final Object object = listeners[i];
				if (object instanceof IExecutionListenerWithChecks) {
					final IExecutionListenerWithChecks listener = (IExecutionListenerWithChecks) object;
					listener.notEnabled(getId(), e);
				}
			}
		}
	}
	/**
	 * Notifies the execution listeners for this command that an attempt to
	 * execute has failed because there is no handler.
	 * 
	 * @param e
	 *            The exception that is about to be thrown; never
	 *            <code>null</code>.
	 */
	private final void fireNotHandled(final NotHandledException e) {