started the implementation of selectabkle nodes (related to issue #16 : https://github.com/miho/VWorkflows/issues/16)
just like the window control nodes can define whether they are selectable (related to issue #16 : https://github.com/miho/VWorkflows/issues/16)
nodes are selectable (related to issue #16 : https://github.com/miho/VWorkflows/issues/16)
ui supports node selection (related to issue #16 : https://github.com/miho/VWorkflows/issues/16)
fixing java 7 support. 

Lamdas are too tempting...
fixing java 7 support. 

We need the final keyword again :(
Update README.md