Ports table item autoalign from Bay (#6946)

Made it so items get their pixel x/y reset on pickup.
    Thrown items now also get their pixel placement slightly randomized.
    Tweaked the center of mass on a boatload of items to be more accurate to their sprite art.
    Replaced a bunch of randomized pixel placement code into a unifying proc; randpixel_xy() that uses an item's randpixel var.

code/modules/mining/mine_items.dm

@@ -115,6 +115,7 @@
 	return	unwield()
 
 /obj/item/weapon/pickaxe/pickup(mob/user)
+	..()
 	unwield()
 
 /obj/item/weapon/pickaxe/attack_self(mob/user as mob)