Comment or refactor void pointers

[no-lex]

Many locations in the code use pointers of type void, which nullifies the type safety that normal pointers have. While this isn't necessarily bad, potentially dangerous pointers like these should have comments nearby to explain what about the code requires such a void pointer, to avoid future misinterpretation of behavior.

By doing so, it may become clear that another C++ feature would do the same thing in a less dangerous way, in which case that method should be used instead.