Updated CHAIDtree and CARTree cookbooks based on the meta vector/matrix access merged by Heiko. They're still failing in some target languages though.
Also working on serializing RefCount from SGVector. Ran into a bug when trying to include cereal header files in SGVector.h. Now this bug is solved but the inheritance serialization is still not working. Hopefully can be solved tmr. Will clean up what I had for serialization tomorrow and hopefully have some follow-up work on linalg (remove old sum methods, etc.)
