Implementation of MARS leakage calculation
Leakage values in MARS and ctapipe are different due to a different definition of the last two rings of camera pixels, see e.g. https://indico.mpp.mpg.de/event/7443/contributions/23043/attachments/15522/17889/magic-cta-borderpixels.png for the outermost ring. Time ago @damgreen shared a code snippet to get the outermost ring as in MARS. I also added the code to get the "outer ring" i.e. the second ring used for the calculation of leakage2, see code snippet $119.
Code in the hillas_preprocessing scripts should be updated to get the leakage calculation as in MARS.