RGB Pointcloud and Live Camera Tracking on Pointcloud Viewer

[omarabid59]

I've added the changes from alexanderkoumis repository for RGB pointcloud visualization.

Also, I've added a nifty feature to toggle Live Camera Tracking on the pointcloud viewer using either dynamic reconfigure or by hitting the m key. For a visualization of this, please see this Wiki.

Finally, I've added the ability to output the rendered pointcloud display as a topic. This is set to disabled by default. To enable, see `lsd_slam_viewer/src/settings.cpp or using dynamic reconfigure.