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
if (DEBUG_COMMAND_EXECUTION) {
			Tracing.printTrace("COMMANDS", "execute" + Tracing.SEPARATOR 
					+ "not handled: id=" + getId() + "; exception=" + e); 
		}
		if (executionListeners != null) {
			final Object[] listeners = executionListeners.getListeners();
			for (int i = 0; i < listeners.length; i++) {
				final IExecutionListener listener = (IExecutionListener) listeners[i];
				listener.notHandled(getId(), e);
			}
		}
	}
	/**
	 * Notifies the execution listeners for this command that an attempt to
	 * execute has failed during the execution.
	 * 
	 * @param e
	 *            The exception that has been thrown; never <code>null</code>.
	 *            After this method completes, the exception will be thrown
	 *            again.
	 */
	private final void firePostExecuteFailure(final ExecutionException e) {
		
		if (DEBUG_COMMAND_EXECUTION) {
			Tracing.printTrace("COMMANDS", "execute" + Tracing.SEPARATOR 
					+ "failure: id=" + getId() + "; exception=" + e); 
		}
		if (executionListeners != null) {
			final Object[] listeners = executionListeners.getListeners();
			for (int i = 0; i < listeners.length; i++) {