migrate to async IO model

new PIIODevice::interrupt() virtual method
new PIWaitEvent private class
PIEthernet and PISerial basically tested on Windows and Linux

libs/main/io_utils/piconnection.cpp

@@ -1115,7 +1115,7 @@ PIVector<PIIODevice * > PIConnection::DevicePool::boundedDevices(const PIConnect
 PIConnection::DevicePool::DeviceData::~DeviceData() {
 	if (rthread) {
 		rthread->stop();
-		rthread->interrupt();
+		if (dev) dev->interrupt();
 		if (!rthread->waitForFinish(1000))
 			rthread->terminate();
 		delete rthread;