Add missing fields like high and low limit.
Array type entries are currently not used and may be deleted in future.
Add add_client_sdo_callback(SDOReceivedCallback) (callback signature void(const SDOResponse&)) and/or add_request_callback(node_id, SDORequestCallback) (listening only for SDOs with slave's own node_id, callback signature void(index, subindex)).
Add send_response(node_id, index, subindex, vector<uint8_t> data) (chooses segmented/expedited transfer on it's own).
Add abort_transfer(node_id, index, subindex, errorcode).
Maybe we should introduce a specific exception if types don't match.
Maybe we could be less restrictive for integer types of different size (e.g casting uint16_t to uint32_t should be safe).