Added wrapper around Steamworks leaderboards
Allow querying leaderboards from menu code
Add DefaultLeaderboards addon metadata, for which boards to show in menu
Format for substituting in dates to default leaderboard names
Let date formats like yy-MM-dd survive string.ToTitleCase()
Added yy-MM-dd date format tests for string.ToTitleCase()
Use DateTime.UtcNow.Date for date substitution in leaderboard names
Get rid of LeaderboardSort enum, just use a bool IsAscending
Made Leaderboard const fields private
Rename GameIdent to PackageIdent in new leaderboard wrapper
Make LeaderboardEntry.Details internal for now