Provide more command line help

In this change I propose an alternative help message for command line users which lists all available commands and the associated parameters. This makes activator commands and sub commands more discoverable.
Your point makes sense about listing this second, but I guess I'd still drop "the recommended way" sentence - I just don't think it will mean anything to anybody. The thing to do instead is be clear that you get command line mode unless you use "ui" and people can decide if they like command line or UI. Language nitpick, maybe "or open a project creation UI" (insert "open").

So my suggestion might be:
```
Open the project in the UI if executed from an existing project directory, otherwise open a project-creation UI.
```

?