FLASH4 complete API

     Creates the named log file and writes some header information
     to it, including the included units, runtime parameters,
     physical constants.  Meta data about the run is also stored
     like a time stamp, the run dimensionality, compiler flags and
     more.  The logfile can be stamped from any unit to store the
     simulation's progress.

     The name of the parameter file is taken as an input; it is
     echoed to the log file.  Only the master processor actually
     writes anything.  In order to avoid accidentally overwriting an
     important logfile during a science run, the logfile is always
     opened in append mode.