Initial ascii-art graph layout

Lately, a lot of buzz has been going on with the new graph viewer implemented on top of RConsCanvas, which renders the basic blocks graph of a function using ascii art. Today we get an initial layout implemented by pancake which is just a PoC. It’s an initial work to implement the proper layouting algorithm to make the graph look more natural and readable by humans. Additionally the ? key in VV (visual graph) view now shows the help message explaining how to: