New option --noscript turns off script scanning

I often need something like this when creating and testing new service
probes. It's handier than modifying script.db every time to remove
the "version" category.

NmapOps.h

@@ -377,6 +377,7 @@ class NmapOps {
 
 #ifndef NOLUA
   int script;
+  bool noscript;
   char *scriptargs;
   char *scriptargsfile;
   int scriptversion;