Adds lava interaction (#4037)

Adds lava interaction: humans walking on lava titles will suffer a slowdown then being set on fire, cyborgs and simple mobs will only take burn damage.

Added the lava and basalt turfs to a random map generator, and replaces the tundra's ocean with the title just named water.

code/modules/mining/mine_turf_types.dm

@@ -12,7 +12,7 @@
 			/turf/simulated/lava,
 			/turf/simulated/mineral
 	)
-	openspace_override_type = /turf/simulated/open/chasm/airless
+	movement_cost = 4	//moving on lava should slows you down
 
 // Custom behavior here - we want smoothed turfs to show basalt underneath, not lava.
 /turf/simulated/lava/get_smooth_underlay_icon(mutable_appearance/underlay_appearance, turf/asking_turf, adjacency_dir)
@@ -22,6 +22,38 @@
 		underlay_appearance.icon_state += "[rand(0,12)]"
 	return TRUE
 
+/turf/simulated/lava/Entered(atom/movable/AM, atom/oldloc)
+	if(istype(AM, /mob/living))
+		var/mob/living/L = AM
+		if(locate(/obj/structure/lattice/catwalk, src))	//should be safe to walk upon
+			return 1
+		if(!istype(oldloc,/turf/simulated/lava))
+			to_chat(L, "<span class='warning'>You are covered by fire and heat from entering \the [src]!</span>")
+		if(ishuman(L))
+			L.fire_stacks += 25
+			L.IgniteMob()
+			L.bodytemperature += 150
+			return 1
+		if(isrobot(L))
+			L.adjustFireLoss(rand(10,30))
+			return 1
+		if(isanimal(L))
+			var/mob/living/simple_animal/H = L
+			if(H.flying) //flying mobs will ignore the lava
+				return 1
+			else
+				H.adjustFireLoss(rand(20,40))
+		else
+			L.adjustFireLoss(rand(10,50))
+	..()
+
+/turf/simulated/lava/Exited(atom/movable/AM, atom/newloc)
+	if(istype(AM, /mob/living))
+		var/mob/living/L = AM
+		if(!istype(newloc, /turf/simulated/lava))
+			to_chat(L, "<span class='warning'>You climb out of \the [src].</span>")
+	..()
+
 // Special asteroid variant that goes with lava better.
 /turf/simulated/floor/asteroid/basalt
 	name = "basalt"
@@ -35,7 +67,6 @@
 	light_color = LIGHT_COLOR_LAVA
 	smooth = SMOOTH_FALSE
 	canSmoothWith = null
-	openspace_override_type = /turf/simulated/open/chasm/airless
 
 	footstep_sound = "concretestep"