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/DefaultOperationHistory.java
* If the operation eligible for undo is not in a state where it can be undone,
 * then no undo is available. No other operations are consulted. Likewise, if
 * the operation available for redo cannot be redone, then no redo is available.
 * </p>
 * 
 * @since 3.1
 */
public class DefaultOperationHistory implements IOperationHistory {
	/**
	 * This flag can be set to <code>true</code> if the history should print
	 * information to <code>System.out</code> whenever notifications about changes
	 * to the history occur.
	 */
    public static boolean DEBUG_OPERATION_HISTORY_NOTIFICATION = false;
	
	/**
	 * This flag can be set to <code>true</code> if the history should print
	 * information to <code>System.out</code> whenever an unexpected condition
	 * arises.
	 */
    public static boolean DEBUG_OPERATION_HISTORY_UNEXPECTED = false;
	
	/**
	 * This flag can be set to <code>true</code> if the history should print
	 * information to <code>System.out</code> whenever an undo context is disposed.
	 */
    public static boolean DEBUG_OPERATION_HISTORY_DISPOSE = false;
	
	/**
	 * This flag can be set to <code>true</code> if the history should print