shows results of removing client/mob verbs on client

[Ruzihm]

Closes #2342.

The verb list classes didn't override ContainsKey, ContainsValue, or RemoveValue, which led to verb removal not working as expected. I also added an explicit verb refresh step to appearance updates on the client side. to ensure that atom verb updates are kept up to date on the client.

Also, while testing listx.Remove(listx) I had an issue where the list was being modified while iterated over so now list.remove will copy lists passed as arguments before iterating over them.

Testing code on top of testgame:

/mob 
	// ...

	verb/thing1()
		world.log << "thing1"
		for(var/i=src.verbs.len, i>=1, i--)
			src.verbs.Remove(src.verbs[i])
	
	verb/thing2()
		world.log << "thing2"
		src.verbs.Remove(src.verbs)

	verb/thing3()
		world.log << "thing3"
		for(var/i=src.verbs.len, i>=1, i--)
			src.verbs -= src.verbs[i]

	verb/thing4()
		world.log << "thing4"
		src.verbs -= src.verbs

/client		
	verb/thing5()
		world.log << "thing5"
		for(var/i=src.verbs.len, i>=1, i--)
			src.verbs.Remove(src.verbs[i])

	verb/thing6()
		world.log << "thing6"
		src.verbs.Remove(src.verbs)

	verb/thing7()
		world.log << "thing7"
		for(var/i=src.verbs.len, i>=1, i--)
			src.verbs -= src.verbs[i]

	verb/thing8()
		world.log << "thing8"
		src.verbs -= src.verbs

Results: thing1-4 remove the mob verbs, thing5-8 remove the client verbs.

[Ruzihm]

This is causing way too much overhead when connected to a real server. Will need an alternative to this....

[Ruzihm]

I'm a little unsure what else could be done here. Ideally, we would only update verbs for clients which are gaining or losing executable verbs.

But I'm wondering if it's acceptable to do something simple and just have the client periodically call RefreshVerbs on a timer of some kind...

[Ruzihm]

This works but I'm not sure if this is the best way.

[Ruzihm]

Also I noticed that when reading/clearing client.verbs, I can see/remove builtins like /client/verb/Center, /client/verb/Northwest, and so on. So clearing client.verbs actually makes the character stop responding to the arrow keys in TestGame. In Byond, they are not included in client.verbs and not removable. That's probably worthy of a different PR/issue.