The original idea of returning pointers is that handles can be moved.
The problem is that the implementation didn't take that in mind and made
everything harder to work with. This commit drops pointer to handles and
returns the handles themselves. While it is still true that handles can
be invalidated, this way we get an old handle instead of a dangling
pointer.
This problem can be solved in the future with sparse buffers.
Uses a std::string_view instead of a std::string, given the pointed to
string isn't modified and is only used in a formatting operation.
This is nice because a few usages directly supply a string literal to
the function, allowing these usages to otherwise not heap allocate,
unlike the std::string overloads.
While we're at it, we can combine the address formatting into a single
formatting call.
ReinUsesLisp