Method move_assign

Libs/sol/sol.hpp:9177–9184

		}

		lua_State* move_assign(lua_State* L, lua_State* rL, stateless_reference&& r) {
			if (valid(L)) {
				deref(L);
			}
			ref = r.ref;
			r.ref = LUA_NOREF;
			return rL;
		}

	protected:
		int stack_index() const noexcept {