Merge pull request #35 from mlosch/master

Graph visualization in rviz.
Merge pull request #36 from mlosch/master

Do not revisit nodes in shortest path finding
Merge pull request #37 from mlosch/master

more eyecandy. (threshold as circles drawn)
Merge pull request #38 from mlosch/master

Object support in graph
untested new brain
Merge remote-tracking branch 'upstream/master'
new brain runs
Merge branch 'master' of https://github.com/tobiasandersson/robot_ai
fix placenode
slightly less dumb intersection handling
Merge remote-tracking branch 'tobias/master'
merge brain