Change the positioning.generate-reference-points option to offer
multiple choices (false, mesh, list, both) and add the
positioning.generated-points-list to allow the user to specify a list of
reference points to generate.
The new class Autocalibration contains the code from the former huge
function Stock::generate_reference_point(). It is refactored a bit, but
still needs work. The function Stock::generate_reference_points() stays
in the Stock class for now.
To be consistent with the other modules, the positioning server must be
called OwlPS Positioner instead of Positioning, and the executable
owlps-positionerd (even if the daemon mode is not implemented yet).
That's a big commit for a tiny change.