uuid: added a uuid module

Only contains a function for (the most useful) uuid4 at present.

uuid.lua

@@ -0,0 +1,31 @@
+--[[
+    uuid generation
+]]
+
+local path = (...):gsub("uuid", "")
+
+local uuid = {}
+
+--helper for optionally passed random; defaults to love.math.random if present, otherwise math.random
+local _global_random = math.random
+if love and love.math and love.math.random then
+	_global_random = love.math.random
+end
+
+local function _random(min, max, r)
+	return r and r:random(min, max)
+		or _global_random(min, max)
+end
+
+local uuid4Template = "xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx"
+
+--generate a UUID version 4 (random)
+function uuid.uuid4()
+    return uuid4Template:gsub("[xy]", function (c)
+        -- x should be 0x0-0xF, the single y should be 0x8-0xB
+        -- 4 should always just be 4 (denoting uuid version)
+        return string.format("%x", c == "x" and _random(0x0, 0xF) or _random(0x8, 0xB))
+    end)
+end
+
+return uuid