improve LaserProperty and subclasses: add .equals(), .hashCode() so that the GUI can compare laserProperties and see if they have been changed
also add .toString() for some of the subclasses - helpful for the dummy driver

Fix: Optimizer compared End with End instead of End with Start
Improved: Optimizer can invert element if faster

Dithering algorithms don't have internal variables for source and target, but they are provided as method arguments

EpilogDriver Fix: Wrong resolutions for EpilogZing. Also split a job if the parts have different resolutions