Revision 3778

Serialization.cpp: Fix compatibility issues with new 2nd custom data type

* When encoding serialised data stream: always write 2nd custom data type
  name to data type blob, and append it actually to the end of the data
  type blob (not somewhere in the middle), no matter if a 2nd custom type
  is actually present (i.e. empty string) in object's data type or not.

* When decoding a serialised data stream: check the size of the data type
  blob, if the blob size is longer than a Srx v1.0 format data type blob,
  then assume there is a 2nd custom data type name, so read it (it might
  be an empty string if 2nd custom data type was not present on encoding
  side's object).

* Bumped version (4.2.0.svn16).