Bug 88838 [Undo] - API cleanup - remove IContextConsultingOperationApprover
Early on this was involved in scenarios where editors examined other operations. This is no longer used. Operation approvers generally apply to all contexts and are installed at the OperationHistory level. Until there is a concrete need for this API it should be removed. It is gratuitous at this point.
bundles/org.eclipse.core.commands/src/org/eclipse/core/commands/operations/IOperationHistory.java
* redone. Operations are added to the history once they have been initially
 * executed. Clients may choose whether to have the operations history perform
 * the initial execution or simply add the operation to the history.
 * </p>
 * <p>
 * Once operations are added to the history, the methods <code>canRedo()</code>
 * and <code>canUndo()</code> are used to determine whether there is an
 * operation available for undo and redo in a given operation context. The
 * context-based protocol implies that there is only one operation that can be
 * undone or redone at a given time in a given context. This is typical of a
 * linear undo model, when only the most recently executed operation is
 * available for undo. When this protocol is used, a linear model is enforced by
 * the history. It is up to clients to determine how to maintain a history that
 * is invalid or stale. For example, when the most recent operation for a
 * context cannot be performed, clients may wish to flush the history for that
 * context.
 * </p>
 * <p>
 * Additional protocol allows direct undo and redo of a specified operation,
 * regardless of its position in the history. When a more flexible undo model is
 * supported, these methods can be implemented to undo and redo directly
 * specified operations. If an implementer of IOperationHistory does not allow
 * direct undo and redo, these methods can return a status indicating that it is
 * not allowed.
 * </p>
 * <p>
 * Listeners (IOperationHistoryListener) can listen for notifications about
 * changes in the history (operations added or removed), and for notification
 * before and after any operation is executed, undone or redone. Notification of
 * operation execution only occurs when clients direct the history to execute