Allow listing variables and folders inside of variable folders

[Jowan-Spooner]

This means there is no need to access the variable dictionary directly.

Dialogic.VAR.my_folder.variables() # returns an array of the variables
Dialogic.VAR.my_folder.variables(true) # returns an array of the variables as absolute (e.g. my_folder.my_variable)
Dialogic.VAR.my_folder.variables().pick_random() # returns a random variable in this folder

Dialogic.VAR.locations.folders().pick_random().variables().pick_random() # picks a random location in a random location folder

These methods do also work on the root Dialogic.VAR level.

Also adds folder.has() method so you can check

Dialogic.VAR.my_folder.has("Variable")

(as you could on the root level already)

I think this is a cool change allowing to get more information from the variables without accessing Dialogic.current_state_info["variables"] directly.