[B.A.T.M.A.N.] /proc vis rework

Hi Folks

A while back i suggested we re-work the /proc/net/batman/vis format. Attached are two patches to achieve this. One patch is for the kernel model sources and the second extends batctl so that it can read from the /proc file and output dot or json format as before. The patch includes documentation for the new new batctl command in the man page.

I've tested the dot output using graphviz dot. However i don't have any tools which use the json output. So that format is not tested.

Andrew