New Commands API

[prokopyl]

The goal of this new version is to bring more flexibility and new features to the already existing API :

• A commands tree model, enabling single commands and n-deep sub-commands to be registered.
• Refactoring the Command class to be only a read-only execution context, allowing deferred (or threaded) usage.
• Genericizing commands, so they can share similar behaviour when used in different sub-commands.
• Adding localization to the help texts and messages.

[Vlammar]

Composite can be a good thing. For example when you need an optionnal width and length. In the actual state you have to check in the plugin if there is none or both. Adding a solution like an optionnalComposite will allow to solve this issue, something like this

@About("Size")
@Flag(composite = {"w","h"}
public OptionnalComposite<ArrayList<Composant<Integer>>> size;

@About("The width")
@Flag(shortName = "w")
public Composant<Integer> width;

@About("The height")
@Flag(shortName = "h")
public Composant<Integer> height;

[prokopyl]

Made obsolete by #55