Daniel Jacobs

Note, if I don't derive from `py::trampoline_self_life_support`, the code still compiles and runs without any lifetime issues (and the warning goes away of course).

Seeing that it works without deriving from `py::trampoline_self_life_support`, I'm curious as to what the purpose of inheriting from this class is?

> Or do you think we need to PYBIND11_EXPORT ‘trampoline_self_life_support’? (I hope not, but it totally depends, I guess.) I'm curious, why would we not export this symbol? Seems like...