Add Keysight branding where applicable

Because there is now more than one "product name" per device
type, we have a concept of a "generic product name" which
singularly maps onto a device type.

This change comes with a few small breaking changes within
the C++ API:

DeviceType::GetDeviceTypeString has been renamed to
DeviceType::GetGenericProductName to denote that
the returned value is not device specific and
device->getProductName() is preferable.

The member function DeviceType::toString has been renamed
to DeviceType::getGenericProductName for the same reason.

The DeviceType std::ostream& operator<< has been removed
to avoid accidental use of the generic product name.

device/device.cpp

@@ -81,7 +81,7 @@ uint16_t Device::getTimestampResolution() const {
 
 std::string Device::describe() const {
 	std::stringstream ss;
-	ss << getType() << ' ' << getSerial();
+	ss << getProductName() << ' ' << getSerial();
 	return ss.str();
 }