orml_traits::parameter_type_with_key looks doesn't support one more key-value definition.

[Dengjianping]

If this macro supports constant k-v definition, it would be nice.

orml_traits::parameter_type_with_key! {
    pub KV1: |key| => val {};
    pub KV2: |key| => val {};
    ...
    pub KVn: |key| => val {};
}