libevent fully refactored

[paolopas]

As I did for the LibBoostAsioHandler and the LibUvHandler, now it's time for LibEventHandler too.

This version implements heartbeat and offers the same functionality as the other handlers (finally a fix for #330.) The example code has also been updated to do exactly the same things as the other examples.

This will allow for quick comparisons between different handlers, in terms of usage and perhaps benchmarking. Certainly, if you encounter problems with a handler, you can now quickly check whether changing handler solves the problem.

I don't think I could give a better Christmas present to AMQP-CPP, which can finally boast a large selection of handlers, all fully functional. Although I shouldn't say anything about libev...

I must confess that at the underlying library level, libevent left me pleasantly impressed and I recommend it for its ease of use, the richness of its APIs and the truly complete documentation it has.

As usual, for those impatient and eager to try it, here it is.

Important

libevent_2025-12-20.zip

@brentnd I hope you don't mind me brushing up your code, but it was about time.