Add profile to enable debugging
Give more info when ij.jar is missing
Make Apple-JVM-specific function name clearer

The set_path_to_apple_JVM function (formerly set_path_to_JVM)
specifically looks for Apple JVMs in OS X's JavaVM framework folder
(typically in /System/Library/Java/JavaVM.Framework/Versions).

If such a JVM is found, it sets the OS-X-specific JAVA_JVM_VERSION
environment variable to match it; and if not, the function errors out.
Issue a warning if CFStringGetCString call fails
Make set_path_to_apple_JVM use return codes

That way, we'll be able to tell whether it successfully
found an Apple JVM and set the JAVA_JVM_VERSION property.
Remind that the JVM here is an Apple Framework one