Adding a getPlayers accessor to Roster.
Starting work on a Season simulator.

Adding internal classes for "slots" in a starting lineup, player status
(injury, etc.), as well as a starting lineup class itself.

Working through this, I see that I will need a "matchups" class too, to
track which Managers are going head-to-head each week.
Added the RB/WB slot.
Moving the Slot interface to a separate file.
Added the LeagueRules object.

LeagueRules captures the drafting and scoring rules for a particular
league.
Passing LeagueRules as a param to SeasonSimulator.