More key chords for --bind

Close #1752

src/tui/light.go

@@ -345,6 +345,14 @@ func (r *LightRenderer) GetChar() Event {
 		return Event{BSpace, 0, nil}
 	case 0:
 		return Event{CtrlSpace, 0, nil}
+	case 28:
+		return Event{CtrlBackSlash, 0, nil}
+	case 29:
+		return Event{CtrlRightBracket, 0, nil}
+	case 30:
+		return Event{CtrlCaret, 0, nil}
+	case 31:
+		return Event{CtrlSlash, 0, nil}
 	case ESC:
 		ev := r.escSequence(&sz)
 		// Second chance

src/tui/tcell.go

@@ -284,6 +284,12 @@ func (r *FullscreenRenderer) GetChar() Event {
 			return Event{keyfn('z'), 0, nil}
 		case tcell.KeyCtrlSpace:
 			return Event{CtrlSpace, 0, nil}
+		case tcell.KeyCtrlBackslash:
+			return Event{CtrlBackSlash, 0, nil}
+		case tcell.KeyCtrlRightSq:
+			return Event{CtrlRightBracket, 0, nil}
+		case tcell.KeyCtrlUnderscore:
+			return Event{CtrlSlash, 0, nil}
 		case tcell.KeyBackspace2:
 			if alt {
 				return Event{AltBS, 0, nil}

src/tui/tui.go

@@ -40,6 +40,12 @@ const (
 	ESC
 	CtrlSpace
 
+	// https://apple.stackexchange.com/questions/24261/how-do-i-send-c-that-is-control-slash-to-the-terminal
+	CtrlBackSlash
+	CtrlRightBracket
+	CtrlCaret
+	CtrlSlash
+
 	Invalid
 	Resize
 	Mouse