Added OxyImage/Palette unit test [discussion:453825]
Added OxyImage/Palette unit test [discussion:453825]

sevoku/oxyplot,Kaplas80/oxyplot,Jonarw/oxyplot,oxyplot/oxyplot,GeertvanHorrik/oxyplot,Mitch-Connor/oxyplot,H2ONaCl/oxyplot,br111an/oxyplot,objorke/oxyplot,svendu/oxyplot,Sbosanquet/oxyplot,br111an/oxyplot,shoelzer/oxyplot,svendu/oxyplot,sevoku/oxyplot,HermanEldering/oxyplot,Rustemt/oxyplot,Rustemt/oxyplot,DotNetDoctor/oxyplot,Isolocis/oxyplot,BRER-TECH/oxyplot,bbqchickenrobot/oxyplot,olegtarasov/oxyplot,svendu/oxyplot,Mitch-Connor/oxyplot,Mitch-Connor/oxyplot,Sbosanquet/oxyplot,H2ONaCl/oxyplot,as-zhuravlev/oxyplot_wpf_fork,Kaplas80/oxyplot,objorke/oxyplot,objorke/oxyplot,freudenthal/oxyplot,lynxkor/oxyplot,br111an/oxyplot,NilesDavis/oxyplot,TheAlmightyBob/oxyplot,as-zhuravlev/oxyplot_wpf_fork,as-zhuravlev/oxyplot_wpf_fork,mattleibow/oxyplot,Rustemt/oxyplot,jeremyiverson/oxyplot,freudenthal/oxyplot,zur003/oxyplot,GeertvanHorrik/oxyplot,olegtarasov/oxyplot,Sbosanquet/oxyplot,GeertvanHorrik/oxyplot,HermanEldering/oxyplot,shoelzer/oxyplot,DotNetDoctor/oxyplot,TheAlmightyBob/oxyplot,shoelzer/oxyplot,freudenthal/oxyplot,bbqchickenrobot/oxyplot,BRER-TECH/oxyplot,TheAlmightyBob/oxyplot,lynxkor/oxyplot,H2ONaCl/oxyplot,mattleibow/oxyplot,bbqchickenrobot/oxyplot,lynxkor/oxyplot,jeremyiverson/oxyplot,jeremyiverson/oxyplot,ze-pequeno/oxyplot,Jofta/oxyplot