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
* @return The {@link ParameterType} for the parameter with the provided id
	 *         or <code>null</code> if this command does not have a parameter
	 *         type with the provided id.
	 * @throws NotDefinedException
	 *             If the handle is not currently defined.
	 * @since 3.2
	 */
	public final ParameterType getParameterType(final String parameterId)
			throws NotDefinedException {
		final IParameter parameter = getParameter(parameterId);
		if (parameter instanceof ITypedParameter) {
			final ITypedParameter parameterWithType = (ITypedParameter) parameter;
			return parameterWithType.getParameterType();
		}
		return null;
	}
	/**
	 * Returns the {@link ParameterType} for the return value of this command or
	 * <code>null</code> if this command does not declare a return value
	 * parameter type.
	 * 
	 * @return The {@link ParameterType} for the return value of this command or
	 *         <code>null</code> if this command does not declare a return
	 *         value parameter type.
	 * @throws NotDefinedException
	 *             If the handle is not currently defined.
	 * @since 3.2
	 */
	public final ParameterType getReturnType() throws NotDefinedException {
		if (!isDefined()) {