Fix https://github.com/gizak/termui/issues/10

Handle CJK wide characters in helper.go
Add multi width text ouput support in widgets

example/list.go

@@ -20,8 +20,8 @@ func main() {
 
 	strs := []string{
 		"[0] github.com/gizak/termui",
-		"[1] editbox.go",
-		"[2] iterrupt.go",
+		"[1] 你好，世界",
+		"[2] こんにちは世界",
 		"[3] keyboard.go",
 		"[4] output.go",
 		"[5] random_out.go",

example/par.go

@@ -24,11 +24,11 @@ func main() {
 	par0.Y = 1
 	par0.HasBorder = false
 
-	par1 := termui.NewPar("Simple Text")
+	par1 := termui.NewPar("你好，世界。")
 	par1.Height = 3
 	par1.Width = 17
 	par1.X = 20
-	par1.Border.Label = "Label"
+	par1.Border.Label = "标签"
 
 	par2 := termui.NewPar("Simple text\nwith label. It can be multilined with \\n or break automatically")
 	par2.Height = 5