Introduce the concept of Command Groups for better organization and management

[Crystalwarrior]

Focusing on the "play music and fade in" part, this sequence looks like an absolute mess:

So perhaps a concept of "groups" can be introduced to allow you to organize it? Currently, branches can fulfill this purpose:

Another reference of this concept being applied is http://aaonline.fr case maker, though it's far more hard-coded and you can only assign 1 extra action to each "frame":

Ideally, the above image would be condensed to just this and only this, where you could open up an advanced view to modify each individual part:

So the goal is to create a Grouping system that gives you a descriptive preview of the sequence of commands, while being easy to modify, and expand on by plugins like Textalog so a special purpose-built Group Editor can be made with intent of creating visual novel scenes.

Related issues:
#92
#54