Progress bars + Wall Rationalization

This commit does the following:
 - Ports progress bars from -tg- (tgstation/-tg-station#9921)
 - Refactors wall attackby code to make it 100% less insane; Instead of
   manually checking every little thing, it uses do_after,
   consequentially, making the new progress bars affect dealing with walls
   as well.

Wall code makes a tiger sad.

code/modules/mining/coins.dm

@@ -133,7 +133,7 @@
 		flick("coin_[cmineral]_flip", src)
 		icon_state = "coin_[cmineral]_[coinflip]"
 		playsound(user.loc, 'sound/items/coinflip.ogg', 50, 1)
-		if(do_after(user, 15))
+		if(do_after(user, 15, target = src))
 			user.visible_message("<span class='notice'>[user] has flipped [src]. It lands on [coinflip].</span>", \
 								 "<span class='notice'>You flip [src]. It lands on [coinflip].</span>", \
 								 "<span class='notice'>You hear the clattering of loose change.</span>")

code/modules/mining/drilling/scanner.dm

@@ -12,7 +12,7 @@
 
 	user << "You begin sweeping \the [src] about, scanning for metal deposits."
 
-	if(!do_after(user,50)) return
+	if(!do_after(user,50, target = src)) return
 
 	if(!user || !src) return
 

code/modules/mining/mine_turfs.dm

@@ -362,7 +362,7 @@ var/global/list/rockTurfEdgeCache
 		user << "<span class='notice'>You start picking...</span>"
 		P.playDigSound()
 
-		if(do_after(user, P.digspeed))
+		if(do_after(user, P.digspeed, target = src))
 			if(istype(src, /turf/simulated/mineral)) //sanity check against turf being deleted during digspeed delay
 				user << "<span class='notice'>You finish cutting into the rock.</span>"
 				P.update_icon()