Add "AddNotUniqueRangeItemsTest"
Add IsUnique readonly property to SortedCollection

Change AddExistsTest for not unique SortedCollection
Add new test - "AddExists_IsUniqueTest" for unique SortedCollection
Add "AddNotUniqueRangeItems_IsUniqueTest"
Change SortedCollection to use generics

Chage tests to use SortedCollection<int>
Add Comparer property to compare two items
Add ability to change sort direction to SortedCollection

Add property SortDirection
Add test SortDirectionTest
Add SortedCollection.UpdateItems to change items after SortDirection changed
Add ability to change Comparer

Add CustomComparerTest
Add events to monitor change Comparer, SortDirection and Count
Add test to check raising events
Add documentation
Add "RemoveTest"
Add "RemoveAtTest"
Add "ClearTest"
Add Documentation