trunc.lua

local function utf8sub(str, start, numChars)
	local currentIndex = start
	while numChars > 0 and currentIndex <= #str do
		local char = string.byte(str, currentIndex)
		if char >= 240 then currentIndex = currentIndex + 4
		elseif char >= 225 then currentIndex = currentIndex + 3
		elseif char >= 192 then currentIndex = currentIndex + 2
		else currentIndex = currentIndex + 1 end
		numChars = numChars - 1
	end
	return str:sub(start, currentIndex - 1)
end