port-mp-setups: a bunch of bug fixes

- only load the MP setup file when loading the agent, instead of when entering CS
- "clear default" was cause the game setup to become invalid upon re-entering it
- all challenges were showing the same text

src/include/types.h

@@ -3776,8 +3776,10 @@ struct menudata_main {
 struct menudata_mpsetup {
 	u32 slotindex;
 	u32 slotcount;
-	u8 showpresets;
 	u32 unke24;
+	u32 unke28;
+	u32 unke2c;
+    u8 showpresets;
 };
 
 struct menudata_mppause {
@@ -3990,9 +3992,9 @@ struct menu {
 		struct menudata_filemgr fm;
 		struct menudata_main4mb main4mb;
 		struct menudata_training training;
+        struct menudata_mpsetup mpsetup;
 	};
 
-	struct menudata_mpsetup mpsetup;
 };
 
 struct gamefile {