Register int02 handler (nmi); disable NMI by default.

Rename handle_nmi to handle_02 to be more consistent with other handlers.
Actually register handle_02.
Don't panic in nmi handler - just log by default.
Set the disable nmi bit when accessing the cmos index register.
diff --git a/src/post.c b/src/post.c
index f681f01..73cd798 100644
--- a/src/post.c
+++ b/src/post.c
@@ -47,6 +47,7 @@
         set_irq(i, entry_hwpic2);
     // Initialize software handlers.
+    set_irq(0x02, entry_02);
     set_irq(0x10, entry_10);
     set_irq(0x11, entry_11_official);
     set_irq(0x12, entry_12_official);