Use the type key factory methods more
Added support for separate keys for default and implmentation
Switch more method calls to use type keys
Switch more method calls to use type keys
Relaxed node type bounds for OrganisedTreeBuilder to allow the BinarySearchTree type key to work
More use of type key and bounds changes
Switch more method calls to use type keys
Allow exactly specified trees to be represented by type keys
Relaxed node iterator type constraints so they can iterate over a subtype of the node specified by the tree used to create them
Added note to changelog