Add Levenshtein distance functions to string lib

[Beherith]

--- Calculates edit distance of two strings, O(n*m) time, O(n) memory
	---@param a string
	---@param b string
	---@return number 

	function string.Levenshtein(a,b)

	--- Finds string that is closest to a in a table
	---@param a string
	---@param t table, primarily values are strings, keys can be strings too
	---@return string, number bestresult, bestscore
	function string.FindClosest(a,t)

[salinecitrine]

What's the use case for this? Probably worth mentioning in the PR description.

[WatchTheFort]

@Beherith What is the status of this?

[WatchTheFort]

@Beherith Is this ready to merge?

[WatchTheFort]

@Beherith Is this ready to merge?

[salinecitrine]

tests pass

[salinecitrine]

Suggested change

	function string.FindClosest(a,t)
	function string.findClosestString(a,t)