-----------------------------------------
	Description of the jsonevtloop and schema
	-----------------------------------------

Purpose: JSON-based asynchronous API for signal-cli.

This mode is not intended to be used directly from the command line, but to 
provide an easy use API for other scripting languages.

signal-cli listens for JSON requests on stdin. Each JSON request must be
a single valid JSON object (enclosed in {}), followed by LF. The JSON text
itself hence must not contain linefeeds (only escaped as \n and no pretty
printing enabled).

When incoming messages are received from the signal back-end, they are
in turned JSON encoded and sent out on stdout.

Any error messages or debug information is sent out on stderr as expected.



JSON Schema Version 2 


	JSON Requests are read from STDIN in "jsonevtloop" mode and the Reponses are
	sent to STDOUT in "jsonevtloop" mode
	
	Generic Request attributes valid for ALL requests
	{
		"reqType": "<request-type>",				// MANDATORY: Name of request type
		"reqID": <integer or string>				// Optional: reqID that will be present in the 
													// response message for async callers to use as transaction id
													// (note: for brevity omitted in the examples below)
	}
	Generic Response attributes valid for ALL responses
	{
		"respType": "<response-type>",				// Name of response type
		"apiVer": 2,								// API Version 2
		"reqID": <object>,							// Request Identifier as present in the request object
		"status": "<ok|error>",						// Whether the request was a success of failure
		"message": "<error-message>"				// In case of status="error", this contains any error message
	}

	
	Send Message Request (direct message to another person)
	{
		"reqType": "send_message",
		"recipientNumber": "<number>",
		"messageBody": "<message-body-text>",
		"attachments": [ "<file-name1>", ... ]
	}

	
	Message Envelope Received, sent to group chat with some attachements present
	{
	  "apiVer": 2,
	  "respType": "envelope",
	  "reqID": null,
	  "status": "ok",
	  "envelope": {
	    "source": "+46123456",
	    "sourceDevice": 1,
	    "relay": null,
	    "timestamp": 1581272926239,
	    "isReceipt": false,
	    "dataMessage": {
	      "timestamp": 1581272926239,
	      "message": "😋😋😋",
	      "expiresInSeconds": 0,
	      "attachments": [
	        {
	          "contentType": "image/jpeg",
	          "filename": "signal-2020-02-09-122846.jpeg",
	          "id": "8983570171695764643",
	          "size": 569218
	        },
	        {
	          "contentType": "image/jpeg",
	          "filename": "signal-2020-02-09-122846.jpeg",
	          "id": "4282268489503632431",
	          "size": 629080
	        },
	        {
	          "contentType": "image/jpeg",
	          "filename": "signal-2020-02-09-122846.jpeg",
	          "id": "1780607521773749056",
	          "size": 595515
	        },
	        {
	          "contentType": "image/jpeg",
	          "filename": "signal-2020-02-09-122846.jpeg",
	          "id": "119656560176959856",
	          "size": 311650
	        }
	      ],
	      "groupInfo": {
	        "groupId": "FRasdb6mSVwHwetHSX8mkjQ==",
	        "members": null,
	        "name": null,
	        "type": "DELIVER"
	      }
	    },
	    "syncMessage": null,
	    "callMessage": null,
	    "receiptMessage": null
	  }
	}



	Alive Request
	Test if signal-cli is still responding
	{
		"reqType": "alive"
	}

	Alive Response
	{
		"respType": "alive"
	}
	

	Exit Request		
	Request immediate termination of signal-cli client
	{
		"reqType": "exit"
	}
	
	Exit Response to an exit request
	Indicated the exit was due to an exit request as opposed to an error
	{
		"respType": "exit",
		"status": "ok"
	}
	
	Exit Response due to an unrecoverable error
	{
		"respType": "exit",
		"status": "error",
		"message": "<error-message>"
	}
	
	Generic Error Response
	{
		"respType": "error",
		"status": "error",
		"message": "<error-message>"
	}