Add `string:trim8()` and fix intllib

builtin/common/misc_helpers.lua

@@ -207,6 +207,10 @@ function string:trim()
 	return (self:gsub("^%s*(.-)%s*$", "%1"))
 end
 
+function string:trim8()
+	return utf8.gsub(self, "^%s*(.-)%s*$", "%1")
+end
+
 --------------------------------------------------------------------------------
 function math.hypot(x, y)
 	local t

builtin/intllib/gettext.lua

@@ -20,7 +20,7 @@ local function parse_po(str)
 	end
 	for _, line in ipairs(str:split("\n")) do repeat
 		lineno = lineno + 1
-		line = line:trim()
+		line = line:trim8()
 
 		if line == "" or line:match("^#") then
 			state, msgid, msgid_plural = nil, nil, nil

builtin/intllib/lib.lua

@@ -56,12 +56,12 @@ function intllib.load_strings(filename)
 	end
 	local strings = {}
 	for line in file:lines() do
-		line = line:trim()
+		line = line:trim8()
 		if line ~= "" and line:sub(1, 1) ~= "#" then
 			local pos = find_eq(line)
 			if pos then
-				local msgid = unescape(line:sub(1, pos - 1):trim())
-				strings[msgid] = unescape(line:sub(pos + 1):trim())
+				local msgid = unescape(line:sub(1, pos - 1):trim8())
+				strings[msgid] = unescape(line:sub(pos + 1):trim8())
 			end
 		end
 	end