- There is now also a configurable limit on the actual size
  of cache elements, including a limit on the maximal size
  of a single cache element
- Pinned elements also count towards the size.
- Results are only inserted into the cache once they are fully
  computed.
- If a result is requested from the cache, while it is still
  being computed, this computation can be awaited. This
  functionality existed before, but is now encapsulated
  in a separate CacheAdapter class. This encapsulation allows
  us to test this functionality which was previously untested.
- Removed thread-safety from the cache class itself,
  As it can be added easily using ad_utility::Synchronized

…annah on these tests, and make them pass deterministically.

…apter)

Still missing: Cache size which is settable from the commandline.

Added commandline support for the cache configuration and renamed several constants.

…-cpu machine.