Include at least function names in the release binary

[helgoboss]

Right now, we strip away all debug info. This is especially bad on macOS, where resolving symbols against something like a PDB doesn't really work (yet). If function names or even line numbers would be there, it would help much in case of panics of even hard crashes.

[helgoboss]

On Windows, I can't get good function names in the panic stack trace, no matter what. Fortunately, the PDB approach "resolve symbols" works where in most cases.