Adding B Field to gear file generated by LCIOWriter

I am using a patched EUTelescope version that should be able to reconstruct even in presence of a magnetic field. Even though I am not using that functionalities, some processors search for a magnetic field in the gear file and they crashes if they can't find it. It could easily fixed in EUTelescope, but I noticed that all the gear files in the examples have the B field defined in the gear file, even if it is zero.