Fix destructors should be public virtual

[Rayman]

I encountered some compilation errors with clang. It complains that the destructor is not virtual. According to the cpp core guidelines a destructor should be either public and virtual or protected and non virtual. See also this link: https://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines#c35-a-base-class-destructor-should-be-either-public-and-virtual-or-protected-and-non-virtual