Remove specific dependency in field_divB0

[krystophny]

GORILLA/SRC/field_divB0.f90

Line 67 in 4cfe407

use tetra_grid_settings_mod, only: g_file_filename, convex_wall_filename, iaxieq_in !=> Michael Eder, 05 May 2022

This makes it hard to decouple code and leads to "yet another variant of field_divB0.f90". Check also similar things elsewhere.

[krystophny]

possible solution: add namelist section specifically for field_divB0 members and move the variables into a module inside field_divB0.f90.

[krystophny]

Oh no it gets worse. Any workaround I tried to at least set the variables is prohibited by the well-meant protected flag.

GORILLA/SRC/tetra_grid_settings_mod.f90

Line 27 in 2d54b35

character*64,public,protected :: g_file_filename