• Fixed bug where passing a reference to a different DBM::Deep object
  would still result in an internal reference.
  
• Added export() method for recursively extracting hashes/arrays into
  standard in-memory Perl structures.
  
• Added import() method for recursively importing existing Perl hash/
  array structures
  
• Fixed bug where optimize() wouldn't work if base level of DB was
  an array instead of a hash.