Do a refactor of command parsing in lpxclient and lpxserver

luprex/cpp/core/world.hpp

@@ -200,7 +200,7 @@ public:
     // from the stringstream.  If the lua expression returns a
     // value, that is also printed to the stringstream.
     //
-    eng::string probe_lua(int64_t actor_id, const eng::string &lua);
+    eng::string probe_lua(int64_t actor_id, std::string_view lua);
 
     // Probe the 'interface' function of the specified sprite.
     //