Have log_prefix-and-_level imply -j LOG

...and track which modules/targets we have made.  Better doc changes needed.
Prepend -p and -j options to command line

    Instead of appending (so that they come first and load their respective
    modules if necessary).  This fixes the bug where iptables rules would
    load on some machines (where they happened to be in the right order) and
    not in others (where, for example, the --dports argument would come before
    -p tcp).

    Also, ensure we do not call -j or -p arguments more than once.  Thus for
    example, log_level implies -j LOG, so it is neither required nor
    forbidden to add "jump => LOG".