Adding features to Moo command line util.

[ExternalReality]

This commit refactors and cleans up Moo a bit. I find the code easier to extend in this form. I took some liberties with the representation of command options as they are now parsed with System.Console.GetOps and they are represented as just plain strings. Last, the order of required arguments and optional arguments to the Moo command has been transposed due to the way GetOpt works. Let me know if this patch is acceptable. If not, let me know what changes need to be made to make it acceptable.

By the way, I am partial to the code style used by the Snap Web Framework. I hope this is not a problem.

Regards,
Eric

[jtdaugherty]

Thanks! This is great. I only have one small request, which is that the blocks of docstrings (e.g., those containing "------") be changed to Haddock syntax and the long lines of dashes be removed. Other than that, thanks a ton! If that sounds reasonable to you, do that and I'll accept.

For future reference, large commits are a bit harder for me to evaluate. This one isn't, chiefly because it mostly moves code around, but smaller, more incremental changes will be much easier to measure.

Thanks for putting time into this!

[ExternalReality]

Sounds reasonable.