FPE in do_scan_grid during fast_scan_grid

[rjfarmer]

https://testhub.mesastar.org/rf%2Ffpe/commits/0fbd67e/test_cases/astero/fast_scan_grid

In do_param we start at k=max_parameters and work down the list. But param(max_parameters) is not set. The set_starting_values call only initializes the param's that are set, not the unset ones.