Bug 425

The intention is to provide a way of using the promote, demote and delete
functions from LayerManager2 in an application template directly.  This should
be possible, but it may require changes.

There are a couple of ways of doing this.

1. GeoDan provided implementations of promote and demote widgets, we could use
those and develop an additional delete widget

2. we could add the promote, demote, and delete functionality to the
legendtemplate widget and use a single widget that has different modes.  This
was done for the ROIManagerMode, for instance. 

3. some other way that I haven't thought of yet ;)

There are implications for the LayerManager2 widget, it should use the same
mechanism so we don't end up with multiple ways of doing it.  The current
LayerManager2 widget maintains a separate map session so changes can be
cancelled.  Embedding the controls in the main page would imply that the changes
cannot be cancelled (although they could be 'undone', that's a new feature for
another bug discussion).  I need to evaluate the impact of that on the 'popup'
mode of the layermanager2 widget.