KPS4_3L does not repect changes to the polars after precompilation

[ufechner7]

The functions rad_cl_mtk and rad_cd_mtk are not part of the model struct and can therefore not be changed after pre-compilation. This should be fixed as it was already done for KPS4 and KPS3. This has no negative impact on the performance.

[1-Bart-1]

Same problem with the symbolic calc_acc_speed and calc_acc_torque functions as they use se("system_3l.yaml"). This is more difficult to solve as the @register_symbolic function only seems to work globally.

[ufechner7]

Same problem with the symbolic calc_acc_speed and calc_acc_torque functions

New issue for the problem with these functions: #73

Let's solve one issue at a time.