Convert scheduler.py to use argparse

[ghost]

Thus removing non-standard-library docopt dependency.

[prophile]

Why is the docopt dependency a problem?

[ghost]

Why use docopt when you can use argparse?

[ghost]

(argparse does type checking and management of mutually-exclusive arguments for you)

[prophile]

Likewise: why use argparse when you can use docopt? It's simpler, less code, and easier to modify.

[ghost]

Ok, if you want to keep docopt, keep docopt.

But IMO, this:

match_count = args.matches

is better than this:

match_count = int(options['<matches>'])

and using something from the standard library that's fit-for-purpose is better than an external dependency.

[prophile]

You do raise a good point on not having to do the conversions manually.

I'm not sure I entirely agree with the argument that anything is better purely by dint of its being in the standard library, particularly with proper dependency management.

I'm not averse to merging this in principle - anyone else feel strongly one way or the other?