ERT-651: Added @rtype: Attributes
ERT-651: Changed hasBlock() to __contains__()
ERT-651: Renamed delBlock() -> deleteBlock()
ERT-651: Removed size() methods - use len().
ERT-651: Using 0 <= index < len in __getitem__()
ERT-651: Added setParent() calls to returned child objects.
ERT-651: Added functionality to export cell information.