Add LAAS geomaps (gdal)

Maps have their own directory
Add mission description.
Add robot description
Fix maps paths
Add mission loader.

Also used for display.
Clean up in patrolling_mission.py
Add sampling for robot accessible positions
Test accessible positions sampling
Improve display (add color choice)
Refactoring: geomap are a new module
Move sampling function into geomaps module
Add dummy motion links and display them
Hint to display visibility links