let each file register its own constants with Lua

stepmania/src/PlayerNumber.cpp

@@ -3,8 +3,16 @@
 #include "ThemeManager.h"
 #include "GameState.h"
 #include "CommonMetrics.h"
+#include "LuaManager.h"
 
 
+void LuaPlayerNumber(lua_State* L)
+{
+	FOREACH_PlayerNumber( pn )
+		LUA->SetGlobal( ssprintf("PLAYER_%d",pn+1), pn );
+}
+REGISTER_WITH_LUA_FUNCTION( LuaPlayerNumber );
+
 PlayerNumber GetNextHumanPlayer( PlayerNumber pn )
 {
 	for( PlayerNumber p=(PlayerNumber)(pn+1); p<NUM_PLAYERS; ((int&)p)++ )