Add "-n" option to Simfactory

Add a "do-nothing" option to Simfactory. It would parse its input, say what it would do, but not actually do it.

Frank says:

"With this in mind it might be also good to have a 'noop' option for submit which would print, in nice long language, what it would do, for example (please improve): "'submitting job on 16 nodes using 32 MPI processes with 4 threads per process (2 processes with a total of 8 threads per node).' "I would totally use this before a lot of my job submissions. :)"

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