We are trying to tackle Issue 332: (Arithmetic protocol should be removed from Collections and Strings)

The problem is that the chronology classes in Pharo depend on the arithmetic of Collection to perform time computation. So there is two things. We remove the Collection-arithmetic from Core and we propose: - move the Colllection arithmetic stuff in an extension package, so that if people want to use it, they can - rewrite the Chrono stuff so that they do their computation without Collection arithmetics.