fixed to the new model organization
nogil for base function calculation
vectorizing functions
vectorizing functions and removing non-vectorized
fixed non-linear equations for imperfections
fixed non-linear equations for imperfections
fixed the arc-length method and added log messages
calc_f_ext() is now a non-invisible class method, removed old main code
added j0 values
changed j0 from 0 to 1, it was making the non-linear analysis not working
removed setup for non-implemented case
fixed vectorized functions