Use OrderedDict from DataStructures instead of Dict?

[kmundnic]

This is an enhancement only, and not related to functionality.

For easier viewing/printing of the options, I think it would be neat to use an OrderedDict from the DataStructures package instead of a Dict. This will preserve the order of the arguments when the dictionary is read after creation. This would make the loop

for (arg,val) in parsed_args
    println("  $arg  =>  $val")
end

print the output in the same order as the arguments were given.