Mars PEM:
New Boolean options for following orbital parameters of ob_ex_lsp.asc: var_obl, var_ex, var_lsp.
If using evol_orbit_pem=true, you can specify which parameter to follow.
True by default: Do you want to change the parameter XXX during the PEM run as prescribed in ob_ex_lsp.asc.
If false, it is set to constant (to the value of the tab_cntrl in the start)
RV