Codechange: Let the compile generate the master command table out of templated command traits.

This is using a non-intrusive type-traits like templated system, which
allows compile-time validation that the command table and the command
enum match up.

src/viewport.cpp

@@ -88,6 +88,7 @@
 #include "command_func.h"
 #include "network/network_func.h"
 #include "framerate_type.h"
+#include "viewport_cmd.h"
 
 #include <forward_list>
 #include <map>