Clean up of the code before and after minfx execution.
This includes a number of simplifications. pre_command_feed_back() is now called
initial_printout(). post_command_feedback() has been deleted. This was for a kludge which can be
avoided by setting the minfx printout arg to zero. The calls to set_generic_pre_and_post_amble()
and set_grid_pre_and_post_amble() were part of this kludge and are eliminated. The self.silence
flag is now used to silence printouts when desired.
