MT_WALLSPIKE bumps are now literally reusing wallspring code

The code clearly *wanted* them to behave like wallsprings, but it was a mess so they were instead nuclear railguns. Now they're grey springs with damage but without tiregrease!

Also:
- Fixes pop-out wallspike interactions
- If a custom MF_SPRING has a "starcolor" (tiregrease stars) of SKINCOLOR_NONE, instead don't apply any tiregrease

src/info.c

@@ -5016,7 +5016,7 @@ mobjinfo_t mobjinfo[NUMMOBJTYPES] =
 		14*FRACUNIT,    // height
 		0,              // display offset
 		4,              // mass
-		0,              // damage
+		45*FRACUNIT,    // damage
 		sfx_None,       // activesound
 		MF_NOBLOCKMAP|MF_NOGRAVITY|MF_SCENERY|MF_NOCLIPHEIGHT|MF_PAPERCOLLISION|MF_NOHITLAGFORME|MF_DONTENCOREMAP,  // flags
 		S_NULL          // raisestate

src/k_kart.c

@@ -1225,6 +1225,20 @@ boolean K_KartSolidBounce(mobj_t *bounceMobj, mobj_t *solidMobj)
 		return false;
 	}
 
+	if (solidMobj->type == MT_WALLSPIKE)
+	{
+		// Always thrust out towards the tip
+		// (...don't try to roll our own bad calculations,
+		// just make this behave like a wallspring...)
+
+		P_DoSpringEx(bounceMobj, mapobjectscale, 0, solidMobj->info->damage,
+			solidMobj->angle, SKINCOLOR_NONE);
+
+		K_PlayerJustBumped(bounceMobj->player);
+
+		return true;
+	}
+
 	// Adds the OTHER object's momentum times a bunch, for the best chance of getting the correct direction
 	{
 		distx = (bounceMobj->x + solidMobj->momx) - (solidMobj->x + bounceMobj->momx);
@@ -1252,16 +1266,6 @@ boolean K_KartSolidBounce(mobj_t *bounceMobj, mobj_t *solidMobj)
 		normalisedx = FixedDiv(distx, dist);
 		normalisedy = FixedDiv(disty, dist);
 
-		if (solidMobj->type == MT_WALLSPIKE)
-		{
-			fixed_t co = FCOS(solidMobj->angle);
-			fixed_t si = FSIN(solidMobj->angle);
-
-			// Always thrust out toward the tip
-			normalisedx = FixedMul(normalisedx, abs(si)) - co;
-			normalisedy = FixedMul(normalisedy, abs(co)) - si;
-		}
-
 		bounceSpeed = FixedHypot(bounceMobj->momx, bounceMobj->momy);
 		bounceSpeed = FixedMul(bounceSpeed, (FRACUNIT - (FRACUNIT>>2) - (FRACUNIT>>3)));
 		bounceSpeed += minBump;

src/p_map.c

@@ -323,7 +323,7 @@ P_DoSpringEx
 		P_InstaThrust(object, finalAngle, finalSpeed);
 	}
 
-	if (object->player)
+	if (object->player && starcolor != SKINCOLOR_NONE)
 	{
 		K_TumbleInterrupt(object->player);
 		P_ResetPlayer(object->player);
@@ -1341,6 +1341,11 @@ static BlockItReturn_t PIT_CheckThing(mobj_t *thing)
 						thing->y,
 						g_tm.thing->z + (P_MobjFlip(thing) > 0 ? g_tm.thing->height : -thing->height)
 					);
+
+					if (g_tm.thing->type == MT_WALLSPIKE)
+					{
+						K_KartSolidBounce(thing, g_tm.thing);
+					}
 				}
 			}
 			else
@@ -1367,6 +1372,12 @@ static BlockItReturn_t PIT_CheckThing(mobj_t *thing)
 		if (!P_IsObjectOnGround(g_tm.thing) && g_tm.thing->momz * P_MobjFlip(g_tm.thing) < 0) // fell into it
 		{
 			P_DamageMobj(g_tm.thing, thing, thing, 1, DMG_TUMBLE);
+
+			if (thing->type == MT_WALLSPIKE)
+			{
+				K_KartSolidBounce(g_tm.thing, thing);
+			}
+
 			return BMIT_CONTINUE;
 		}
 		else