Refactor Animation to be a member of Petrack

Refactor Animation in such a way, that it is instantiated directly with Petrack, so other modules can rely on its reference.

Although Animation is only dependant on Petrack, it is not created as a member variable, but as a pointer to be initialized later in the constructor of Petrack (and never changes again). This comes with drawbacks when trying to make dependencies of modules explicit.

This issue is a subtask of MR !378 (merged)