Disabled removal of retracted IUs from InputBuffer to
match the Python version - since it is an item of discussion
that will be resolved in the next version anyway.

- OutputBuffer retracts all remaining live IUs on destruction
- sends correct event type now
- fixed reference error for calling handlers
- setters properly check for retracted flag
- also added some missing checks for committed flag

- OutputBuffer retracts all remaining live IUs on destruction
- sends correct event type now
- fixed reference error for calling handlers
- setters properly check for retracted flag
- also added some missing checks for committed flag

Also removed stray cout lines

Use with Locker, possible in a dedicated stack frame, like this:
// ... code ...
{ // open stack frame
	Locker locker(iu->payload());
	iu->payload()["a"] = "string";
	iu->payload()["b"] = "simultaneouslySentString";
} // close stack frame, sending the update

Also renamed some functions (preserving old names as deprecated aliases)

Also changed constructors of PayloadEntryProxy to protected.

Setting default channel name and default payload type works OK

It is Herwin's resend fix. Test sources are present but not
enabled during library build (will have to implement test build asap).