Fix concurrent-extension race in MMapDirectory.Map, #1090 - #1263

'SortedSet<Util.FSTPath<T>>.Max' is obsolete: 'This property is deprecated because the name does not match the behavior in descending order views. Use TryGetLast(out T) instead.'

'SortedDictionary<int, int>.TryGetPredecessor(int, out KeyValuePair<int, int>)' is obsolete: 'Use TryGetPredecessor(TKey, out TKey, out TValue) or INavigableCollection<KeyValuePair<TKey, TValue>>.TryGetPredecessor(TKey, out KeyValuePair<TKey, TValue>) instead.'

'SortedSet<SearchGroup.MergedGroup<T>>.Min' is obsolete: 'This property is deprecated because the name does not match the behavior in descending order views. Use TryGetFirst(out T) instead.'

'SortedSet<SearchGroup.MergedGroup<T>>.Max' is obsolete: 'This property is deprecated because the name does not match the behavior in descending order views. Use TryGetLast(out T) instead.'

'SortedSet<AbstractGroupFacetCollector.FacetEntry>.Max' is obsolete: 'This property is deprecated because the name does not match the behavior in descending order views. Use TryGetLast(out T) instead.'

'SortedSet<AbstractGroupFacetCollector.FacetEntry>.Max' is obsolete: 'This property is deprecated because the name does not match the behavior in descending order views. Use TryGetLast(out T) instead.'

'SortedSet<int>.Max' is obsolete: 'This property is deprecated because the name does not match the behavior in descending order views. Use TryGetLast(out T) instead.'

'SortedSet<Util.FSTPath<T>>.Min' is obsolete: 'This property is deprecated because the name does not match the behavior in descending order views. Use TryGetFirst(out T) instead.'

'SortedSet<Util.FSTPath<T>>.Max' is obsolete: 'This property is deprecated because the name does not match the behavior in descending order views. Use TryGetLast(out T) instead.'