CHANGES IN VERSION 0.52.0
-------------------------

NEW FEATURES

    o Define the OutOfMemoryObject class (VIRTUAL class with no slots).

    o Add S4 generic containsOutOfMemoryData() and implement various methods.
      See '?containsOutOfMemoryData' for the details.

    o Add S4 generic saveRDS() and a default method that is just a thin wrapper
      around base::saveRDS() that issues a warning if the object to serialize
      contains out-of-memory data.