Add support for the bell "\a" character

Closes #39

examples/terminal/terminal.gd

@@ -2,6 +2,31 @@ extends GDXterm.Terminal
 
 onready var pty = $PTY
 
+var _next_bell := true
+
 
 func _ready():
 	pty.fork(OS.get_environment("SHELL"))
+
+
+func _on_Terminal_bell():
+	# Limit the rate at which bells can be rung in case the user does something crazy such as
+	# `while true; do echo -e "\a"; done`
+	# which causes a real mess if we keep adding AudioStreamPlayers.
+	if not _next_bell:
+		return
+
+	var player := AudioStreamPlayer.new()
+	player.stream = preload("../bell.wav")
+	player.autoplay = true
+	player.connect("finished", self, "_on_player_finished", [player])
+	add_child(player)
+	_next_bell = false
+
+
+func _on_player_finished(player: AudioStreamPlayer):
+	player.queue_free()
+
+
+func _on_Timer_timeout():
+	_next_bell = true

examples/terminal/terminal.tscn

@@ -19,3 +19,10 @@ env = {
 "COLORTERM": "truecolor",
 "TERM": "xterm-256color"
 }
+
+[node name="Timer" type="Timer" parent="."]
+wait_time = 0.1
+autostart = true
+
+[connection signal="bell" from="." to="." method="_on_Terminal_bell"]
+[connection signal="timeout" from="Timer" to="." method="_on_Timer_timeout"]