[Feature Request] Add ability to publish move_base goal by pressing on the map

[jash101]

This would essentially extend ROSboard from a visualization tool to an interactive viz tool, but it can be pretty helpful.

[dheera]

Thank you @jash101 this is a really good suggestion. There are a couple of other suggestions (teleop, service calls) that have been suggested as well and over the next couple weeks I will think about how to generalize this. For example, some people may want to set the move_base goal and others may want to just publish a Pose or PoseStamped or Point when clicked. I'll see if there's a good way to generalize that.