make example usable

 - position particle in simulation box
 - make laser visible
 - set frequency range for radiation to correct maximum of 3.5*(omega_0 gamma^2 *4)
make example 2D capable
add 2D as standard compile test

this allows to check if the radiation works in 2D
Merge pull request #530 from PrometheusPi/fix-SingleParticleRadiationWithLaser_2D

Fix example SingleParticleRadiationWithLaser to work in 2D