Added JPetParamUtils::distanceXY implementation (by Tomasz Bednarski)
Added JPetParamUtils::distanceXY implementation (by Tomasz Bednarski)

JPETTomography/j-pet-framework-examples,wkrzemien/j-pet-framework-examples,JPETTomography/j-pet-framework-examples,wkrzemien/j-pet-framework-examples,JPETTomography/j-pet-framework-examples,wkrzemien/j-pet-framework-examples,JPETTomography/j-pet-framework-examples