- render the whole line where the error/warning points to, if any, and another
line with '^', like other compilers do
- lowercase diagnostic severity
- decapitalize the message if it doesn't start with a proper name
Should be a warning because strictly speaking, the codegen doesn't need it
during the compilation. It's an error at the moment only to let all clients of
Kotlin reflection know that they must include kotlin-reflect.jar in the
classpath