Too early for tests :/
First working version of the cache engine

Seems to make a little sense now. The DS in itself. But only Creates are
done. Should see what surprises R.U and D have for us. Although Deletes
seems to be a pretty hefty operation. Thats already known

Anyway, this is a HUGE commit so bear with me.

* Namespace:
  * not required, thrown away
  * NamespaceEngine, DUH! no necessity anymore
* Structures:
  * Structure doesn't need to store the list of structure instances
    anymore
  * Generates a unique identifier for the namespace-structure-instance
    combination
  * Checks if a given strucure instance is of the same type as defined
    in the base structure
* CacheEngine:
  * THE *main* part of the cache, at least for the time being. Holds all
    the hashes required for the data structure. The API needs to be
    well thought of and maintained properly since this is a Single point
    of failure.