Bug 89020 [Undo] Operation throws assertion failure if undo limit is set to 0
I20050324-0800 Unfortunately existing clients of text's undo manager were allowed to set any number without failing. This is no longer possible: an assertion failure occurrs if the limit is smaller than 1. I will add code on my side that will handle the negative numbers but the operation history must allow 0.
bundles/org.eclipse.core.commands/src/org/eclipse/core/commands/operations/IOperationHistory.java
* <code>REDONE</code> notification.
	 * 
	 * <code>CANCEL</code> severity indicates that the user cancelled the
	 * operation and that the operation remains in the redo history.
	 * <code>ERROR</code> severity indicates that the operation could not
	 * successfully be redone and that it has been removed from the history.
	 * Listeners will also be notified that the operation was removed. Any other
	 * severity code is not specifically interpreted by the history, and is
	 * simply passed back to the caller. For all severities other than
	 * <code>OK</code>, listeners will receive the
	 * <code>OPERATION_NOT_OK</code> notification instead of the
	 * <code>REDONE</code> notification.
	 * 
	 * @throws ExecutionException
	 *             if an exception occurred during redo.
	 * 
	 */
	IStatus redo(IUndoContext context, IProgressMonitor monitor, IAdaptable info)
			throws ExecutionException;
	/**
	 * Redo the specified operation
	 * 
	 * @param operation -
	 *            the operation to be redone
	 * @param monitor -
	 *            the progress monitor to be used for the redo, or code>null</code> if no
	 *            progress monitor is provided
	 * @param info -
	 *            the IAdaptable (or <code>null</code>) provided by the
	 *            caller containing additional information. When this API is