flasher_var_photons not used in light-emission based flasher simulations

[GernotMaier]

This very likely requires a small improvement to ff-1m, as I don't see an option here:

 /workdir/simulation_software/sim_telarray/LightEmission/ff-1m --help
Syntax: /workdir/simulation_software/sim_telarray/LightEmission/ff-1m [ options ]
Options (description [units] {default}):
  --events N[,...]    (Number(s) of events to be simulated {1})
                      (note: this can be a comma-separated list)
  --photons nph[,...] (Number of photons emitted per flasher unit {2500000})
                      (note: this can be a comma-separated list, each for
                      the corresponding number of events)
  --bunchsize f       (Photons per bunch {1.0})
  --xy x,y            (If flasher is displaced w.r.t. axis [cm] {0.,0.})
  --distance d        (Distance of flasher from camera front [cm] {1600.})
  --camera-radius r   (Fiducial radius of camera in detection plane [cm] {120.})
  --spectrum wlen|fname (Wavelength [nm], distribution model, or name of file {400}.)
  --lightpulse duration|fname (Length[,delay] or shape model of emitted light pulse
                       or table name {Simple:0}.)
  --angular-distribution isotropic|fname (Angular distribution {isotropic} or table.)
  --run rn            (Run number recorded {1})
  --altitude  meters  (Altitude of instrument above sea level [m] {2100})
  --atmosphere n|fname (Atmospheric profile table by numer or file name {1})
  -o fname            (Set name of output file {ff-1m.dat.gz}