Port Pachinko to current plugin version

This was mainly a direct reimplementation of each BlockCode program, with a few
tweaks. I had to make the Ball group global so that it shows up in the
“[something] is in group [group ▼]” dropdown. I also added an extra Reset
method on the "Bump!" label to hide it when the game resets, calling it
directly with "call [method] on [node]".

The code that plays one of 5 sounds at random when the ball hits a pin
previously relied on being able to pass an int as the "sound name" parameter,
which would for some reason I didn't bother digging into would previously cause
a str() conversion to be inserted, but now does not.

```gdscript
func _on_body_entered(body: Node2D):
	if body.is_in_group('Ball'):
		PinSound = randi_range(1, 5)
		var __sound_node_1 = get_node(str(PinSound))
		# ...
```

So instead I use a chain of conditionals that compiles to:

```gdscript
func _on_body_entered(something: Node2D):
	if ((something).is_in_group('Ball')):
		PinSound = randi_range(1, 5)
		if PinSound == 1:
			var __sound_node_1 = get_node('1')
			# ...
		elif PinSound == 2:
			# ...
```

This is a bit wordier than what was there before but it works.

It would be nice to have a way to define a local variable rather than a
property of the node, but it's not the end of the world.

https://phabricator.endlessm.com/T35697

JJ:	 M game-04/main.tscn
JJ:	 M game-04/pin.tscn
JJ:	 M project.godot

Author: wjt