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>DONE</code> notification.
	 * 
	 * <code>CANCEL</code> severity indicates that the user cancelled the
	 * operation and that the operation was not added to the history.
	 * <code>ERROR</code> severity indicates that the operation did not
	 * successfully execute and that it was not added to the history. Any other
	 * severity code is not specifically interpreted by the history, and the
	 * operation will not be added to the history. For all severities other than
	 * <code>OK</code>, listeners will receive the
	 * <code>OPERATION_NOT_OK</code> notification instead of the
	 * <code>DONE</code> notification.
	 * 
	 * @throws ExecutionException
	 *             if an exception occurred during execution.
	 * 
	 */
	IStatus execute(IUndoableOperation operation, IProgressMonitor monitor,
			IAdaptable info) throws ExecutionException;
	/**
	 * Return the limit on the undo and redo history for a particular context.
	 * 
	 * @param context -
	 *            the context whose limit is requested
	 * 
	 * @return limit - the undo and redo history limit for the specified
	 *         context.
	 */
	int getLimit(IUndoContext context);
	/**
	 * Get the array of operations in the redo history for a given context. The