Noetic devel

[hap1961]

Updated gscam to work on ROS Noetic / Ubuntu 20.04
It is not intended to be backwards compatible since the currently distributed binary gscam versions work fine on melodic and kinetic and don't need updating. Summary

• Removed ROSBUILD environment usage.
• Moved the launch files from "examples" to "launch"
• Added launch files for our GigeVision camera source plugin, tdgigevsrc, which is the main reason I did this. (My first git / github usage - hope I got the work flow correct)

[Martin-Oehler]

Your commit removes the nodelet library, which breaks nodelet usage.