Adds Variable Click Delay

Now certain weapons can strike faster or slower than usual. No weapons currently do this as this PR just lays the groundwork for that.
The click delay can also be modified with traits. The slime agility modifier makes attacks happen 25% sooner.
Adds debug test verb to display a weapon's DPS. It's really basic but should be sufficient for future force adjustments I might do in the future.

code/modules/organs/organ_external.dm

@@ -411,7 +411,7 @@
 			user << "<span class='warning'>You can't reach your [src.name] while holding [tool] in your [owner.get_bodypart_name(grasp)].</span>"
 			return 0
 
-	user.setClickCooldown(DEFAULT_ATTACK_COOLDOWN)
+	user.setClickCooldown(user.get_attack_speed(tool))
 	if(!do_mob(user, owner, 10))
 		user << "<span class='warning'>You must stand still to do that.</span>"
 		return 0