Read a delivery receipt's body as the octets that arrived (#81)

* Regression tests for a receipt body read under a data_coding it is not written in

* Read a delivery receipt's body as the octets that arrived, not by its data_coding

* Assert SMPPSim's UCS2 receipt body parses like every other segment's

* Record the receipt-body defect as fixed

* Retain a multipart segment's octets once, not twice

* Sort the new type import into its file's order

src/index.ts

@@ -12,13 +12,14 @@ export { types } from './defs/types.ts';
 export {
 	isCommand,
 	isResp,
-	maxPduLength,
 	maxSeqNr,
 	objToPdu,
 	pduReturn,
 	pduToObj,
 } from './pdu.ts';
 
+export { maxPduLength } from './pdu-refusal.ts';
+
 export {
 	bitCount,
 	decodeMessage,