[pocolibs] Improve viam output so it can work for VideoCamera too
[pocolibs] Add some way to export depth image thought Spix3DImage
[doc] add ROS Troubleshooting, fixes #225
[yarp] Provide encoding for some commonly used structure

Include encoding for:
  - mathutils.Vector -> list as sub-bottle
  - mathutils.Matrix -> list of list
  - mathutils.Quaternion -> list (x, y, z, w)
  - mathutils.Euler -> list (yaw, pitch, roll)
  - transformation3D -> list (x, y, z, yaw, pitch, roll)

Fix issue #259
[doc] use openrobots git to be consistent

with both dev/summary and contributing (same §)
[ros] fix typo in GPS publisher

Thanks to Serge Stinckwich for reporting this issue