Adds admin_jump_link and AI eye jumping

Also fixes a little mistake in ghost AI eye following.

code/modules/mob/dead/observer/observer.dm

@@ -499,8 +499,8 @@ This is the proc mobs get to turn into a ghost. Forked from ghostize due to comp
 
 	return ..()
 
-/proc/ghost_follow_link(var/atom/target, var/atom/ghost=src)
-	if(!target) return
+/proc/ghost_follow_link(var/atom/target, var/atom/ghost)
+	if((!target) || (!ghost)) return
 	if(isAI(target)) // AI core/eye follow links
 		var/mob/living/silicon/ai/A = target
 		. = "<a href='byond://?src=\ref[ghost];follow=\ref[A]'>core</a>"

code/modules/mob/hear_say.dm

@@ -55,7 +55,7 @@
 			return
 		if(speaker_name != speaker.real_name && speaker.real_name)
 			speaker_name = "[speaker.real_name] ([speaker_name])"
-		track = "([ghost_follow_link(speaker)]) "
+		track = "([ghost_follow_link(speaker, ghost=src)]) "
 		if(client.prefs.toggles & CHAT_GHOSTEARS && speaker in view(src))
 			message = "<b>[message]</b>"
 
@@ -170,7 +170,7 @@
 	if(istype(src, /mob/dead/observer))
 		if(speaker_name != speaker.real_name && !isAI(speaker)) //Announce computer and various stuff that broadcasts doesn't use it's real name but AI's can't pretend to be other mobs.
 			speaker_name = "[speaker.real_name] ([speaker_name])"
-		track = "[speaker_name] ([ghost_follow_link(follow_target)])"
+		track = "[speaker_name] ([ghost_follow_link(follow_target, ghost=src)])"
 
 	var/formatted
 	if(language)

code/modules/mob/mob_helpers.dm

@@ -475,7 +475,7 @@ var/list/intents = list("help","disarm","grab","harm")
 				if(subject != M)
 					follow = "([ghost_follow_link(subject, ghost=M)]) "
 				if(M.stat != DEAD && M.client.holder)
-					follow = "(<a href='?src=\ref[M.client.holder];adminplayerobservejump=\ref[subject]'>JMP</a>) "
+					follow = "([admin_jump_link(subject, M.client.holder)]) "
 				var/mob/dead/observer/DM
 				if(istype(subject, /mob/dead/observer))
 					DM = subject