Fix bug in NetUP extension. If a pin is connected, ConnectedTo() returns HRESULT S_OK and the pin reference will *not* be null.
Fix pin connection checks. If a pin is not connected, the HRESULT is not S_OK with pin reference null. Rather, the HRESULT is 0x80040209 (DIERR_UNPLUGGED & VFW_E_NOT_CONNECTED). We don't want to throw an exception for these cases.
Fix SAT>IP tuner detection XPath bug and tidy up a few comments.