Patch to add sync() method to Engine and fixes for unit tests on Linux

[Chad Yates]

Attached is a patch to the Persistence Engine and cppunit test suite:

 - Added a new sync() method to Engine using code from ~Engine.

 - Added implementations for std::string << and >> operators (was 
overlooked in  last patch as I was juggling 3 source trees)

 - Applies various fixes/updates to the ccxx_tests cppunit test suite.  
The tests that are active, should compile and run successfully under 
Linux now.

Cheers,

Chad