Update data_cast, remove dynamic_cast
Remove dynamic_cast in XML reader
Custom data variant for TestData
Test class variant of Matrix and Image
Refactor primitive tests
Add cast tests to image and matrix tests
Add data traits, use them instead of classVariant()
Hide trait classes from doxygen
Change implementation of data_cast (no RTTI), code compiles
Fix tests, add cast tests to String
Implement clean static version of Matrix::save()
Data traits for trigger type
Remove Data::classVariant()