Mobs can be incorporeal (#6791)

* Mobs can be incorporeal

Prevents step noises, getting shot, etc. Basically living ghosts. Feel free to add more places this should check, but I think this is a majority.

* Fix missing incorporeal floatyness

code/modules/mob/living/carbon/human/human.dm

@@ -242,6 +242,8 @@
 // this handles mulebots and vehicles
 // and now mobs on fire
 /mob/living/carbon/human/Crossed(var/atom/movable/AM)
+	if(AM.is_incorporeal())
+		return
 	if(istype(AM, /mob/living/bot/mulebot))
 		var/mob/living/bot/mulebot/MB = AM
 		MB.runOver(src)

code/modules/mob/living/carbon/human/human_movement.dm

@@ -204,6 +204,8 @@
 
 // Handle footstep sounds
 /mob/living/carbon/human/handle_footstep(var/turf/T)
+	if(is_incorporeal())
+		return
 	if(!config.footstep_volume || !T.footstep_sounds || !T.footstep_sounds.len)
 		return
 	// Future Upgrades - Multi species support

code/modules/mob/living/carbon/human/life.dm

@@ -612,6 +612,9 @@
 	//Stuff like the xenomorph's plasma regen happens here.
 	species.handle_environment_special(src)
 
+	if(is_incorporeal())
+		return
+
 	//Moved pressure calculations here for use in skip-processing check.
 	var/pressure = environment.return_pressure()
 	var/adjusted_pressure = calculate_affecting_pressure(pressure)

code/modules/mob/living/simple_mob/subtypes/animal/passive/mouse.dm

@@ -54,7 +54,9 @@
 	icon_rest = "mouse_[body_color]_sleep"
 	desc = "A small [body_color] rodent, often seen hiding in maintenance areas and making a nuisance of itself."
 
-/mob/living/simple_mob/animal/passive/mouse/Crossed(AM as mob|obj)
+/mob/living/simple_mob/animal/passive/mouse/Crossed(atom/movable/AM as mob|obj)
+	if(AM.is_incorporeal())
+		return
 	if( ishuman(AM) )
 		if(!stat)
 			var/mob/M = AM

code/modules/mob/mob_movement.dm

@@ -385,6 +385,9 @@
 ///Return 1 for movement 0 for none
 /mob/proc/Process_Spacemove(var/check_drift = 0)
 
+	if(is_incorporeal())
+		return
+
 	if(!Check_Dense_Object()) //Nothing to push off of so end here
 		update_floating(0)
 		return 0