Added basic SBI support

src/main.c

@@ -52,7 +52,7 @@ int main(int argc, char** argv)
 			pthread_mutex_unlock(&cpu0_mutex);
 		}
 
-        fprintf(stderr, "Simulation ended in a non-debug environment\n");
+        fprintf(stderr, "Simulation ended (in a non-debug environment)\n");
         return cpu0->regs.a0;
 	}