network binding should be conditional to relevant preferences

[wxl]

So, we've had network support since version 2.0.2 thanks to 8982c03. It's documented as experimental and off by default in CMakeLists.txt:

qlipper/CMakeLists.txt

Line 50 in 302e2d1

option(ENABLE_NETWORK_CLIPBOARD_SHARING "Enables experimental network support for clipboard sharing" OFF)

Similarly, even if you compile support in, the related preferences are off by default:

qlipper/src/qlipperpreferences.cpp

Lines 226 to 234 in 302e2d1

	bool QlipperPreferences::networkSend() const
	{
	return value("networkSend", false).toBool();
	}
	bool QlipperPreferences::networkReceive() const
	{
	return value("networkReceive", false).toBool();
	}

However, QlipperModel immediately calls QlipperNetwork:

qlipper/src/qlippermodel.cpp

Lines 31 to 34 in 302e2d1

	QlipperModel::QlipperModel(QObject *parent) :
	QAbstractListModel(parent)
	{
	m_network = new QlipperNetwork(this);

This isn't a problem in and of itself, especially considering that the compile-time option renders all of QlipperNetwork's functions essentially no-ops, but what seems a little weird is that a port is immediately bound:

qlipper/src/qlippernetwork.cpp

Lines 53 to 55 in 302e2d1

	m_socket = new QUdpSocket(this);
	bool r = m_socket->bind(QlipperPreferences::Instance()->networkPort(), QUdpSocket::ShareAddress);
	connect(m_socket, SIGNAL(readyRead()), this, SLOT(readData()));

It seems to me that keeping networking ports closed unless needed is a generally good philosophy overall, but especially with "experimental" networking support. Making that binding conditional to one of the two preferences seems a lot more sensible.