restoreMenu: Go to Difficulty select after Match Race, instead of the level selection menu

- Splits M_SetupDifficultyOptions out of M_SetupDifficultySelect.
    - Permits Encore to be handled on Difficulty menu if unlocked after a Match Race.
- Fixes an issue where the in-game Pause menu could be accessed in the menu
    - The prevMenu that was set was overriden with in-game Pause.
    - The assumption made - that the levelsearch/levellist struct would not be touched - is pretty transparently violated.
- I made it go back to the Difficulty select instead of fixing the issue because:
    - Match Race is more dependent on the rules you configure for that particular round
    - This mode of play will be modified in future to not be literally offline MP with things like voting, but instead return to the menu
    - It was easier relative to the amount of work to properly restore (this is the biggest reason)

src/k_menu.h

@@ -760,6 +760,7 @@ extern consvar_t cv_dummykartspeed;
 extern consvar_t cv_dummygpencore;
 extern consvar_t cv_dummymatchbots;
 
+void M_SetupDifficultyOptions(INT32 choice);
 void M_SetupDifficultySelect(INT32 choice);
 void M_DifficultySelectInputs(INT32 choice);
 

src/k_menufunc.c

@@ -384,6 +384,7 @@ menu_t *M_SpecificMenuRestore(menu_t *torestore)
 		if (levellist.newgametype == GT_RACE)
 		{
 			M_SetupRaceMenu(-1);
+			M_SetupDifficultyOptions((cupgrid.grandprix == false));
 		}
 
 		if (!M_LevelListFromGametype(-1))
@@ -409,6 +410,13 @@ menu_t *M_SpecificMenuRestore(menu_t *torestore)
 			}
 		}
 	}
+	else if (torestore == &PLAY_RaceDifficultyDef)
+	{
+		// Handle a much smaller subset of unlock restrictions
+		M_SetupGametypeMenu(-1);
+		M_SetupRaceMenu(-1);
+		M_SetupDifficultyOptions((cupgrid.grandprix == false));
+	}
 	else if (torestore == &EXTRAS_ReplayHutDef)
 	{
 		// Handle modifications to the folder while playing

src/menus/play-local-race-difficulty.c

@@ -71,14 +71,8 @@ static CV_PossibleValue_t dummymatchbots_cons_t[] = {
 };
 consvar_t cv_dummymatchbots = CVAR_INIT ("dummymatchbots", "Off", CV_HIDDEN, dummymatchbots_cons_t, NULL);
 
-void M_SetupDifficultySelect(INT32 choice)
+void M_SetupDifficultyOptions(INT32 choice)
 {
-	// check what we picked.
-	choice = currentMenu->menuitems[itemOn].mvar1;
-
-	// setup the difficulty menu and then remove choices depending on choice
-	PLAY_RaceDifficultyDef.prevMenu = currentMenu;
-
 	PLAY_RaceDifficulty[drace_gpdifficulty].status = IT_DISABLED;
 	PLAY_RaceDifficulty[drace_mrkartspeed].status = IT_DISABLED;
 	PLAY_RaceDifficulty[drace_mrcpu].status = IT_DISABLED;
@@ -106,6 +100,16 @@ void M_SetupDifficultySelect(INT32 choice)
 	{
 		PLAY_RaceDifficulty[drace_encore].status = IT_STRING2|IT_CVAR;	// Encore on/off
 	}
+}
+
+void M_SetupDifficultySelect(INT32 choice)
+{
+	(void)choice;
+
+	// setup the difficulty menu and then remove choices depending on choice
+	PLAY_RaceDifficultyDef.prevMenu = currentMenu;
+
+	M_SetupDifficultyOptions(currentMenu->menuitems[itemOn].mvar1);
 
 	M_SetupNextMenu(&PLAY_RaceDifficultyDef, false);
 }

src/menus/transient/level-select.c

@@ -500,7 +500,7 @@ void M_LevelSelected(INT16 add)
 			}
 			else
 			{
-				restoreMenu = &PLAY_LevelSelectDef;
+				restoreMenu = &PLAY_RaceDifficultyDef;
 			}
 		}
 		else