Speeds up lists massively

[redmoogle]

Partial fix for: #2367

This is alot faster; went from 2.1 minutes with the code in the issue to ~490ms

I'm fairly certain this won't break anything because its just checking if the key exists and instead of manually searching the dictionary I just uses the dictionary search function thats faster (O(n) instead of O(n^2))

[amylizzle]

/proc/RunTest()
	var/list/L = list()
	for(var/i in 1 to 5)
		L.Add("[i]")
		L["[i]"] = "item [i]"
	ASSERT(length(L) == 5)
	ASSERT(L["3"] == "item 3")

should give {"1":"item 1","2":"item 2","3":"item 3","4":"item 4","5":"item 5"} instead gives {"1":"item 1","1":"item 1","2":"item 2","2":"item 2","3":"item 3","3":"item 3","4":"item 4","4":"item 4","5":"item 5","5":"item 5"}

[redmoogle]

/proc/RunTest()
	var/list/L = list()
	for(var/i in 1 to 5)
		L.Add("[i]")
		L["[i]"] = "item [i]"
	ASSERT(length(L) == 5)
	ASSERT(L["3"] == "item 3")

should give {"1":"item 1","2":"item 2","3":"item 3","4":"item 4","5":"item 5"} instead gives {"1":"item 1","1":"item 1","2":"item 2","2":"item 2","3":"item 3","3":"item 3","4":"item 4","4":"item 4","5":"item 5","5":"item 5"}

I just found this out; I got another idea that should be pretty similar though when I get done coding it

[redmoogle]

Im going to close this for now until I figure this out

[redmoogle]

Should be good to rereview now

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