Supports utf8 printing and input

Changes to be committed:
	modified:   src/ltui/label.lua
	modified:   src/ltui/textedit.lua

src/ltui/label.lua

@@ -127,8 +127,20 @@ function label:splitext(text, width)
     for idx = 1, #lines do
         local line = lines[idx]
         while #line > width do
-            table.insert(result, line:sub(1, width))
+            local size = 0
-            line = line:sub(width + 1)
+            for i = 1, #line do
+                if line:byte(i) < 0x80 or line:byte(i) >= 0xc0 then
+                    size = size + 1
+                    if size > width then
+                        table.insert(result, line:sub(1, i - 1))
+                        line = line:sub(i)
+                        break
+                    end
+                end
+            end
+            if size <= width then
+                break
+            end
         end
         table.insert(result, line)
     end

src/ltui/textedit.lua

@@ -77,8 +77,8 @@ function textedit:on_event(e)
 
     -- update text
     if e.type == event.ev_keyboard then
-        if e.key_code > 0x1f and e.key_code < 0x7f then
+        if e.key_code > 0x1f and e.key_code < 0x100  then
-            self:text_set(self:text() .. e.key_name)
+            self:text_set(self:text() .. string.char(e.key_code))
             return true
         elseif e.key_name == "Enter" and self:option("multiline") then
             self:text_set(self:text() .. '\n')
@@ -86,7 +86,11 @@ function textedit:on_event(e)
         elseif e.key_name == "Backspace" then
             local text = self:text()
             if #text > 0 then
-                self:text_set(text:sub(1, #text - 1))
+                local ch_size = -1
+                while text:byte(ch_size) > 0x7f and text:byte(ch_size) < 0xc0 do
+                    ch_size = ch_size - 1
+                end
+                self:text_set(text:sub(1, #text + ch_size))
             end
             return true
         elseif e.key_name == "CtrlV" then