- accelerations in "accelerometer" signal,
  - angular velocities in "gyrometer" signal.

  Head of master does not succeed in compiling. Stop at last version that
  makes the package compile.

  Do not hard code prefix of dependency, use pkg config.

  Since this commit, method push of class Solver takes a task and not anymore
  a task name as input.

  This class is not used in the file and FeaturePositionRelative should be
  prefered.

Minor change: inverse header inclusion order.

Pb and solution pointed out and provided by F. Keith.

This is mandatory to use the device inside the python interpreter.
In addition this commit provides debugging messages when
compiled with VP_DEBUG and when VP_DEBUG_MODE is greater than 25.

But the initializations script are wrong.