Fix chzyer#5, Changed behaviour of delete key

* Changed current delete to CharEOT, added new CharDelete key

wader notes:
Don't expect more char after ex esc rune
Kick reader even if no char is deleted

operation.go

@@ -310,6 +310,13 @@ func (o *Operation) ioloop() {
 				o.t.Bell()
 			}
 		case CharDelete:
+			o.t.KickRead()
+			if o.buf.Len() > 0 || !o.IsNormalMode() {
+				if !o.buf.Delete() {
+					o.t.Bell()
+				}
+			}
+		case CharEOT:
 			if o.buf.Len() > 0 || !o.IsNormalMode() {
 				o.t.KickRead()
 				if !o.buf.Delete() {

terminal.go

@@ -179,7 +179,7 @@ func (t *Terminal) ioloop() {
 				break
 			}
 			isEscape = true
-		case CharInterrupt, CharEnter, CharCtrlJ, CharDelete:
+		case CharInterrupt, CharEnter, CharCtrlJ, CharDelete, CharEOT:
 			expectNextChar = false
 			fallthrough
 		default:

utils.go

@@ -24,7 +24,7 @@ const (
 	CharLineStart = 1
 	CharBackward  = 2
 	CharInterrupt = 3
-	CharDelete    = 4
+	CharEOT       = 4
 	CharLineEnd   = 5
 	CharForward   = 6
 	CharBell      = 7
@@ -49,12 +49,14 @@ const (
 	CharBackspace = 127
 )
 
+// Extra virtual keys
 const (
 	MetaBackward rune = -iota - 1
 	MetaForward
 	MetaDelete
 	MetaBackspace
 	MetaTranspose
+	CharDelete
 )
 
 // WaitForResume need to call before current process got suspend.