Add conversion functions for several API types

Conversion functions have been added for:
- admire::node
- admire::dataset
- std::vector<admire::qos::limit>
- ADM_transfer_t
- ADM_qos_limit_list_t
- ADM_dataset_list_t

Specializations for managed_ctype<T> and managed_ctype_array<T> have
been added for:
- ADM_node_t
- ADM_dataset_t
- ADM_qos_limit_t
- ADM_transfer_t
- ADM_qos_limit_list_t
- ADM_dataset_list_t