optimize ListOrder. avoid stack overflow
update README
Merge pull request #472 from xuwei-k/list-order

optimize ListOrder. avoid stack overflow
add InsertionMap tests
add FingerTree test
WriterTHoist
fix typo
override ephemeralStreamInstance#foldLeft. avoid stack overflow
add EphemeralStream tests
equalContravariant should be implicit val
Merge pull request #475 from xuwei-k/equalContravariant

equalContravariant should be implicit val