* constructor can pass network accessibility as default
* ping URL now constructed in global setup
* watchdog will prevent unnecessary signals by checking if state has really changed (there are redundant QAM signals for QNetworkAccessManager::networkAccessibleChanged)
* refactorings, thread checks
* in case the internet provider is down, this is not detected
* extended test to detect if access is possible
* in case of downtime this indicated in status component
* use doWorkCheck
* relaxed doWorkCheck in unit tests
* removed isShuttingDown, gracefulShutdown
* set timer object name (in case something is wrong, we might see the name in the log)
Up to now we had a mixture of different methods to detect whether
network is connected, accessible or both. Even if they implied a
different meaning, they were all doing the same and internally
referred to almost the same code. Almost, since our implementation
of CNetworkUtils::hasConnectedInterface refers to code from Qt 4.4.
However, all of them returned a boolean status whether a network
interface is generally up or not. Instead of maintaining our own
version, use Qt functions.
refs #869
* new read state "skipped"
* renamed to "isNetworkConnectedAndAccessible"
* checking before reading, which would only fail if network is not accessible
