Implement pcntl_signal()

[pluc]

pcntl_signal is used to handle signals, it would be useful to give CLImate the ability to do something when, for example CTRL+C (SIGTERM) is pressed.

[mikegioia]

@pluc Shouldn't this be handled in your app code? Sort of like:

pcntl_signal(SIGTERM, function ($signo) use ($climate) {
   // $climate->info()...
});