Add double-click picking inside JoglConeRendering sample code

On top of the widgets we also add a picking action on a double click action.

Change-Id: I7631e1541491edd41d49e4f1dfc53ec415a6a2d6
Merge topic 'vtk-java-add-picking-example' into master

2a91342e Add double-click picking inside JoglConeRendering sample code