MAddXYToParticles CoordinateList.l,NumPoints.l,XToAdd.w,YToAdd.w ; Add constants to all particles

Adds constant value XToAdd.w to X.w in the particle list, and constant value
YToAdd.w to Y.w in the particle list. The constants are added to all particles.
To ignore a component, an adder of 0 is permitted. If either of XToAdd or YToAdd
are 0, optimised routines will be used.