make first_range_gate_height channel dependent

[martin-rdz]

As discussed with @HolgerPollyNet, it should be possible to set first_range_gate_height for each channel separately in the config files. Similary to first_range_gate_indx, which is a 1x13 double (in case of arielle). Verlauf can handle this and there seems a different first range gate height for the near range channels.

From my understanding, the variable is renamed firstBinHeight in picassoProcV3 and then used in the pollyPreprocess. However, that would lead to inconsistent height arrays (I guess that is one of the reasons why Verlauf saves the height arrays for FR and NR separately). Probably it is sufficient to consider this offset only for the range correction?