V5sync

[CIPop]

- Reuses MQTTClient as much as possible:
	○ I/O Model:
		§ Sync sending blocking functions that wait completion (ACK / PUBCOMP).
			□ Used for CONNECT/ACK, PUB/ACK, SUB/ACK, DISCONNECTsend
			□ Optionally, a "WithResults" version exists to retrieve data from the ACK
		§ Async receiving callbacks (must exit for the operation to complete)
			□ Used for PUBrecv, AUTH and DISCONNECTrecv
		
	○ #if defined(MQTTV5) used throughout MQTTClient.h/c
	○ One pending operation / call (blocking):
		§ CONNECT /w optional CONNACK information
		§ SUBSCRIBE (one topicFilter) /w optional SUBACK info
	
- NEW: MQTTClient functionality:
	○ PUB /w optional PUBACK/PUBCOMP information (PubDoneData / MQTTPublishWithResults)

- MQTTV5 Client differences:
	○ Ctor will require a reusable MQTTProperties* struct, allocated by the application.
	○ All APIs now accept or return MQTTProperties (CONNECT accepts both connect and will !?)
	○ New APIs, only available in V5:
		- MQTTV5Auth and MQTTV5SetAuthHandler (controlHandler)
		- MQTTV5SetDisconnectHandler (controlHandler)
		- MQTTV5UnsubscribeWithResults + MQTTV5UnsubackData

Open question:

• MQTTV5Packet - For symmetry, should MQTTPacket_willOptions (backed by MQTTPacket_willOptions_initializer) include the MQTTProperties* willProperties?

[vaavva]

Suggested change

	* @param readbuf_size
	* @param readbuf_size
	* @param recvProperties

[vaavva]

Review params for this file - there are a few others missing as well

[CIPop]

Yes - documentation is not ready - sorry I forgot to add that limitation.