poll method
Polls for data available for reading from the serial port.
timeout
can be positive for a timeout in milliseconds, zero for a non-blocking poll, or negative
for a blocking poll.
Returns 'true' on success (data available for reading), 'false on timeout,
Implementation
bool poll(int timeout) {
_checkStatus();
return _checkError(_nativeSerialPool(_serialHandle, timeout)) == 1
? true
: false;
}