Moved data from GameEngine to FarmingTools

I've removed all data from GameEngine to the new FarmingTools class. You
can use the FarmingTools class to get access to the information your
classes need. It exposes all the previous services held by game engine.

Moved InfoUser into App.cs from view model base to make it easier to
user in other code files. This means event aggregator is also in the
app.cs class now.

All classes that were previously singletons are now not. You can access
them statically from the FarmingTools class.