While working on this commit, I noted that to make full use of it,
ListViewItemRenderer needs to have a mode where it allows the icon to
assume it's "natural" size.
But at the moment ListViewItemRenderer explicitly sets the size of the
icon to 16x16 in it's constructor.
What is the preferred solution here?
I think this is probably the best solution:
Document that if you use the "variableItemHeight" you need to set
preferred height and width to -1 on ListViewItemRenderer?
ListViewItemRenderer provides setIconWidth() and setIconHeight()
methods that are a pass-through to the image view's preferred size.
These properties can be set to -1. We could possibly provide a
"variableHeight" boolean property that delegated to these values.
