Remove Wizard and Wicket viewer implementation on basis that shouldn't constrain programming model to this extent.

ie, the work committed in ISIS-800 and ISIS-807.

Instead, should be a separate "add-on"?

Background:

• Jeroen made this suggestion; he thinks that the Wizard interface is too prescriptive
• However Oscar thinks that we should provide a default implementation.

~~~
NB: if we do decide to remove the Wizard from IsIs, then Jeroen and I have registered the "isisaddons.org" domain and the github.com/isisaddons as a domain home for such add-ons.

The idea is to nurture something similar what Apache Wicket do with their "wicketstuff" companion site. All of my com.danhaywood wicket extensions could then move to isisaddons.org.