mv
===
Much like the GNU command by the same name, ``flamke mv`` moves a directory 
from one location to another.  This is primarily used for renaming run directories
from the default values to custom names.  If the new name does not start with the
``run_dir_prefix`` then the new directory is ignored by ``clean``.  Thus this is 
a mechanism for 'saving' runs.

**USAGE**:: 

    flmake mv <src> <dst>

The ``<src>`` argument is the original directory to be moved.  The ``<dst>`` argument
is the target directory where ``<src>`` will be moved.