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
* corresponding value in the map.
	 * 
	 * @param handlersByCommandId
	 *            A map of command identifiers (<code>String</code>) to
	 *            handlers (<code>IHandler</code>). This map may be
	 *            <code>null</code> if all handlers should be cleared.
	 *            Similarly, if the map is empty, then all commands will become
	 *            unhandled.
	 */
	public final void setHandlersByCommandId(final Map handlersByCommandId) {
		
		final Iterator commandIdItr = handlersByCommandId.keySet().iterator();
		while (commandIdItr.hasNext()) {
			getCommand((String) commandIdItr.next());
		}
		
		final Iterator commandItr = handleObjectsById.values().iterator();
		while (commandItr.hasNext()) {
			final Command command = (Command) commandItr.next();
			final String commandId = command.getId();
			final Object value = handlersByCommandId.get(commandId);
			if (value instanceof IHandler) {
				command.setHandler((IHandler) value);
			} else {
				command.setHandler(null);
			}
		}
	}
	/**
	 * Searches for the index of a <code>char</code> in a <code>String</code>