create Manager and Session php class files.
implement Manager class to manager session itself.
implement Session to manager storage.
rename Session and its interface to Storage.
since they stores data into session (or other storage).
rename Manager and its interface to Session.
since they manages Session itself.
create Token module and a trait to load the Token module as preparation.
set request before prepare (preparations may use the request object).
also assign request into response after the respond/prepare is done (request may be altered during respond/prepare).
add requestError and error method to check for error in request such as bad token.
fix initializing session data array.
rename manager as session, which is what it is.
add setup in StorageInterface; remove unused session method.
and construct's phpdoc updated.