Add possibility to define dependencies inbetween pastries

[pampersrocker]

A pastry should have the possibility to define other pastries as dependency. It is possible that a "pastry" may only contain dependencies and no actual data, which is to be interpreted as a container.

[Manuzor]

How would I tell where to install a dependency of a pastry? Should I just install all dependencies to the same destination as the original pastry?

[Manuzor]

For now, dependent pastries will be installed in the same destination as their parent pastry.