JHV 2.0: Implement filter to correct for differential solar rotation

Implement filter to correct for differential solar rotation:

- select point on surface
- calculate solar latitude & longitude of this point
- calculate rotation in degrees for time interval dt_rot (in seconds) between current image and last image:

sin2l = sin(latitude)^2
sin4l = sin2l*sin2l
rotation = 1.e-6*dt_rot*(2.894-0.428*sin2l-0.37*sin4l)*180./pi

; from rotation rate of small magnetic features
; (Howard, Harvey, and Forgach, Solar Physics, 130, 295, 1990)

- calculate horizontal pixel shift s from rotation
- shift ROI of current image by s pixels with respect to last image
- render ROI of current image

- for movie: calculate pixel shifts for all frames when latiude is selected