Refactor Metrics object out of typed course results

[SteveDesmond-ca]

As a developer, I want a single canonical way to access all information about a person's metrics on a given course, so that I can more easily reason about aggregating those metrics.

Acceptance criteria:

• each course contains a Metrics dictionary keyed by Athlete, with a value object containing the following:
  • fastest time
  • best average time (top # threshold...include min/threshold value?)
  • age grade of fastest run (include Athlete in object?)
  • total number of runs
  • total number of miles (still calculate dynamically based on course miles -- should Course be a part of this? -- or cache value?)
  • total time of all runs (new, but should be trivial as part of this)
• Ranked<T> maybe then takes a Func<Metrics, T> for sorting and value mapping?
• a Course's typed results should just rank the Metrics by the relevant property -- this will probably also fix the class size code smell, if things get moved to the right places...

[SteveDesmond-ca]

I think between the new Formattable interface, and the fact that this system is now used by multiple different front-end apps, this is probably no longer relevant, or at the very least not as big of a deal anymore...still worth keeping in mind in the future, perhaps, should new features benefit from it.