Rule Creation Wizard

[JulienCochuyt]

When creating a simple rule, the now more complex Rule Editor can feel uselessly cumbersome.
To remedy this, we will provide a Rule Creation Wizard, simply presenting the first level categories panes of the editor in order as the user clicks "Next".

In a later stage, the wizard might propose pre-selected criteria matching the caret node when possible.
This, however, will more likely be tracked in a subsequent issue.