do not record the bins in the database: it's fast enough to compute them
enable the creation of new once-a boards for different bins tables
rename CPANio::Board::Bins to CPANio::Bins

bins are not stored in the database any more
rename CPANio::Board::OnceA to CPANio::Board::Regular::Releases

a lot of the common features for "regular" boards
now live in CPANio::Board::Regular
move more code in the base class
show a minus if the rank is 0

this can happen when the player with the highest count in the current contest has just fallen
record the board name in the table

this paves the way for more "regular" contests
no default value for author and count

and the attribute name is default_value, anyway
update must be defined in the subclasses
some documentation for the Regular::Releases boards
stop using "board" in an ambiguous way

until we find better names, the current definitions are:
- game:    the game being played (regular releases, regular distributions, etc.)
- period:  for "regular" games, the period considered (month, week, day)
- contest: the sub-contest considered (current, yearly, all-time)
- board:   an actual game leaderboard
pass a list of boards to the templates
use the class instead of __PACKAGE__
update URL to support all "regular" games
rename category_index template to game_index
a template to show a list of leaderboards
a template that describes each game
a template that describes the rules for each period
limit comes from the upper level
the main page is not specific to any game