Use different exit code numbers for different issues

[chu11]

Some resource managers track exit codes, can be useful for debugging.

[chu11]

now that things have been cleaned up/re-architected in magpie 2.0, this is now a much more viable solution to do. Could be something simple like

input check failure - exit 1 setup failure - exit 2 job timeout - exit 3

or would we want to pass back exit code from job?

input check failure - exit 100 setup failure - exit 101 job timeout - exit 102 job failure - return exit ?

[chu11]

in addition, consider #218