L1P Phase2

Draft MR to hold the code for Linear 1 Pass Phase 2 work.EKOS_Linear_Focus_Phase_2.pdf

Starting point was master and then Sophie Taylor's unmerged MR 692 with changes to LM solver and gslhelper.cpp/h and robust statistics.cpp/h.

1. Optimised curve fitting . Should be faster and more accurate and includes outlier rejection.
2. Currently HFR is the only fitting "measure" available. The following have been added: a) HFR Adj (adjusted HFR to compensate for star brightness vs background variation) b) FWHM c) Number stars (max at focus rather than a min) d) Fourier Power (alternative focus method not requiring star detection)
3. Focus units can be displayed in pixels or arc-seconds.
4. Critical Focus Zone - a calculator with 3 different algorithms has been added
5. Focus Offset Utility to automatically build focus offsets.
6. Take flats at same focus point as lights has been fixed.
7. Focus Adviser. Still working on this but a tool to help with focus parameters (since there are now so many).
8. SEP parameters suggestions for focus. Keen to get some feedback on this.
9. Adaptive focus to adapt the focuser position between Autofocus runs, aiming to keep optimum focus for each sub-frame. Adaptations for Temperature and Altitude are supported.
10. Adaptive focuser start . The starting position for an AF run can be filter and Adaptive Focus adjusted.
11. Focus walks added to control how the inward sweep of the AF process performs.
12. AF Overscan originally implemented in the Linear algorithm and then reused by Linear 1 Pass now extended to all focuser movements.