Improved emulation of the SiS 496 chip;

The SMC FDC37C665 Super I/O chip's IDE handler is now disabled for the Rise Computer R418 (the real board by passes that chip's IDE and uses the SiS 496B IDE controller so this is correct and not a hack), fixes hard disks disappearing on soft reset.

src/model.c

@@ -581,7 +581,8 @@ void at_sis496_init()
         at_ide_init();
 	memregs_init();
         pci_init(PCI_CONFIG_TYPE_1, 0, 31);
-        device_add(&sis496_device);
+	sis496_init();
+	trc_init();
 }
 
 void at_r418_init()