Pluto is a superset of Lua 5.4 with a focus on general-purpose programming.
`pluto` feature also enables `lua54` feature since they are compatible and share the same API.
The definition of lua_error in all of Lua 5.1 through 5.4 says lua_error
returns int, but the Rust definition of the same function treats it as
void (because it's known not to return). This causes link-time errors when
building for wasm targets because the wasm linker is aware of function return
types and errors out if they differ between definition and declaration.
Lua 5.4 changed lua_rawlen to return lua_Unsigned, versus size_t in earlier
versions. Change the C API signature to match, and add a wrapper function with
the same name that maintains a stable Rust API by casting to usize.
Alex Orlenko