Unwanted process: Credits are auto-scrolling while invisible

[hsandt]

Currently Credits._process just runs in the wild, even when Credits are not visible (e.g. when touching nothing on the main menu).

I noticed this when logging scrolling value (I'm working on a version that stores float scrolling to support slower scrolling, esp. important on lores pixel art games where 1px/s is very fast).

Credits should either manually return from _process when not visible, or we set its process mode to DISABLED entirely when not visible.

Ex of code hotfix:

func _process(_delta):
	if Engine.is_editor_hint():
		return
	# LOCAL FIX by hsandt to avoid scrolling Credits while invisible,
	# in the background
	if not visible:
		return
	# do stuff...