- Fix JSON and detailed record emitters to use const reference and pointers.
- Fix code to use C++ structured bindings and range-based loops, including reverse() range for locations.
- Eliminate `NL` define for "\n".
- Change JSON emitter to populate `instance_list` in an earlier loop over superclasses instead of a separate loop.
- Rename variables in JSON emitter to conform to LLVM naming conventions.
- Eliminate unused headers in detailed record emitter.