Smarter autoDispose macro.
- Check access, untyped access only when needed.
- null only nullable fields (not Int, Bool, …)
- Skip generating code for @manual dispose()

Smarter addMethod:
- Check if superClass method is inline and can't
  be overridden...
disableFields called the wrong implementation!
Enable autoDispose on everything IDisposable.
Start marking reference-cached objects @borrowed.
Don't spam warnings when super-class inlined
 method was marked @manual.