`make-wt-tree-type``key<?`procedureReturns a new tree type based on the ordering predicate

*key?*, which compares two key values and returns a boolean.*key?*should be a total ordering; for all key values*a*,*b*, and*c*, the following must hold:(key<? a a) ; -> #f (and (key<? a b) (key<? b a)) ; -> #f (if (and (key<? a b) (key<? b c)) (key <? a c) #t) ; -> #t

Two wt-trees are compatible if their tree type objects are

`eqv?`, so trees whose types result from different calls to`make-wt-tree-type`are always incompatible.