P_InitThinkers: Handle several important mobj cleaning tasks in one place, rather than scattered

- titlecam.mobj cannot have P_SetTarget applied when initially setting to NULL, as its previous occupant is some unknown region in memory, and modifying the reference count could in fact change some random number or address ANYWHERE IN THE ENTIRE PROGRAM.
- So we straight up wipe it rather than referenced-unset it in one place, always, for general tidiness.
- Also move skyboxcenterpnts, skyboxviewpnts, and iquetail/iquehead so it's all centralised.

src/d_player.h

@@ -435,6 +435,8 @@ struct altview_t
 	INT32 tics;
 };
 
+extern altview_t titlemapcam;
+
 // ========================================================================
 //                          PLAYER STRUCTURE
 // ========================================================================

src/f_finale.c

@@ -1848,7 +1848,6 @@ void F_StartTitleScreen(void)
 
 		gamestate_t prevwipegamestate = wipegamestate;
 		titlemapinaction = true;
-		P_SetTarget(&titlemapcam.mobj, NULL);
 		gamemap = titleMapNum+1;
 
 		maptol = mapheaderinfo[titleMapNum]->typeoflevel;

src/f_finale.h

@@ -105,9 +105,6 @@ extern UINT16 tttics;
 extern boolean ttavailable[6];
 
 // Current menu parameters
-
-extern altview_t titlemapcam;
-
 extern char curbgname[9];
 extern SINT8 curfadevalue;
 extern INT32 curbgcolor;

src/k_podium.c

@@ -247,8 +247,6 @@ boolean K_StartCeremony(void)
 		&& mapheaderinfo[podiumMapNum]
 		&& mapheaderinfo[podiumMapNum]->lumpnum != LUMPERROR)
 	{
-		P_SetTarget(&titlemapcam.mobj, NULL);
-
 		gamemap = podiumMapNum+1;
 
 		maptol = mapheaderinfo[gamemap-1]->typeoflevel;

src/p_saveg.c

@@ -4526,16 +4526,8 @@ static void P_NetUnArchiveThinkers(savebuffer_t *save)
 	}
 
 	// we don't want the removed mobjs to come back
-	iquetail = iquehead = 0;
 	P_InitThinkers();
 
-	// Oh my god don't blast random memory with our reference counts.
-	waypointcap = trackercap = NULL;
-	for (i = 0; i <= 15; i++)
-	{
-		skyboxcenterpnts[i] = skyboxviewpnts[i] = NULL;
-	}
-
 	// clear sector thinker pointers so they don't point to non-existant thinkers for all of eternity
 	for (i = 0; i < numsectors; i++)
 	{

src/p_setup.c

@@ -8291,9 +8291,6 @@ boolean P_LoadLevel(boolean fromnetsave, boolean reloadinggamestate)
 		K_InitDirector();
 	}
 
-	// clear special respawning que
-	iquehead = iquetail = 0;
-
 	// Initialize ACS scripts
 	if (!fromnetsave)
 	{

src/p_tick.c

@@ -213,10 +213,23 @@ void Command_CountMobjs_f(void)
 void P_InitThinkers(void)
 {
 	UINT8 i;
+
+	for (i = 0; i < NUM_THINKERLISTS; i++)
+	{
+		thlist[i].prev = thlist[i].next = &thlist[i];
+	}
+
+	iquehead = iquetail = 0;
+
 	waypointcap = NULL;
 	trackercap = NULL;
-	for (i = 0; i < NUM_THINKERLISTS; i++)
-		thlist[i].prev = thlist[i].next = &thlist[i];
+
+	titlemapcam.mobj = NULL;
+
+	for (i = 0; i <= 15; i++)
+	{
+		skyboxcenterpnts[i] = skyboxviewpnts[i] = NULL;
+	}
 }
 
 // Adds a new thinker at the end of the list.