Kata: CLI arguments

Parse CLI args into a convenient data structure:
Example:

The schema "d#,b,l*" specifies an int arg -d, a bool arg -b, and a string arg -l
So given args -d10 -b -lINFO

the arg -d has the value 10
the arg -b has the value true
the arg -l has the value "INFO"

Args args = new Args("-d10 -b -lINFO", new Schema("d#,b,l*"));

// Fetch arg's value
Maybe<int> maybeIntArg = args.Integer("d")
maybeIntArg.HasValue             // True
maybeIntArg.Value                // 10

// Can't fetch for non existing arg
Maybe<string> maybeStringArg = args.String("p")
maybeStringArg.HasValue          // False