* scripted_wizard: Make it possible to create target wizard, without the need to add BuildTarget panel

> The old code had a requirement that target wizards must add a BuildTarget
  panel. This is not always convenient for wizard implementer, so I've
  made it possible to make a target wizard without the need to add a
  BuildTarget panel. When this is the case the wizard implementer has the
  task to fully setup the newly added target.

git-svn-id: https://svn.code.sf.net/p/codeblocks/code/trunk@9843 2a5c6006-c6dd-42ca-98ab-0921f2732cef
- scripted_wizard: Use nullptr instead of 0, when dealing with pointers

git-svn-id: https://svn.code.sf.net/p/codeblocks/code/trunk@9844 2a5c6006-c6dd-42ca-98ab-0921f2732cef