AM: timer_scf_chfit is started/stopped in chargefit.f90

This is a parallel context, so that this timer is also started/stopped
on slaves. It seems to be unused there though.
AM: timer_print_scfcycle() is noop if output_unit <= 0
AM: whitespace, rm UB markers
AM: indent the tail section, whitespace
AM: use where necessary, dont try writing trace line on slaves
AM: wip, toggle_legacy_mode() inside of the SCF loop

The exit stategy is ugly. So dont pull it utill the transition is
over.