Adding the ability to trace native methods

[jbachorik]

Resolves #115

With this patch it is possible to trace native methods. There is no difference in usage to the non-native methods.

Eg. the following trace scripts will work on all methods of the Test class regardless of whether they are native or not.

@BTrace                                                                                                                                                                                                       
public class NativeTracker {                                                                                                                                                                           
    @OnMethod(clazz="Test", method="/.*/")                                                                                                                                                         
    public static void nativeMethod(@Self Object self, @ProbeClassName String pcn, ProbeMethodName String pmn, String msg) {                                                                                      
        println("entering: " + pcn + "." + pmn);                                                                                                                                                      
        println("msg = " + msg);                                                                                                                                                                              
    }                                                                                                                                                                                                         
}