Rename o.resolve_all to o.always_resolve

This is the flag for the -R option. "always" is more appropriate than
"all," since "resolveall.nse" does something different, and there is a
"resolve_all" function that does that thing as well, unrelated to the -R
option.

NmapOps.cc

@@ -363,7 +363,7 @@ void NmapOps::Initialize() {
   spoof_mac_set = false;
   mass_dns = true;
   deprecated_xml_osclass = false;
-  resolve_all = 0;
+  always_resolve = false;
   dns_servers = NULL;
   implicitARPPing = true;
   numhosts_scanned = 0;