Allow nodes to be radio buttons

[grapoza]

Need to have related events; radioselected? or just reuse checked?

[grapoza]

This should include emitting treeViewNodeRadioChange

[grapoza]

One possible implementation would be to replace checkable in the node definition with inputType, allowing the input within the label to be any valid input type. The change event can apply to a bunch of input types (and would be ignored otherwise) so a simple rename of the existing event handling could allow that to be reused as well. Appropriate classes/ids could be generated based on the inputType of the node.