add the site icon to the navbar
use the icon as a link to the main page
specify the bins boundaries for each contest
all the boards are now computed by bin/update-boards
s/user/author/g
compute and display authors who just fell off the "current" contest
add forgotten indexes

they were actually live since the beginning, because the site is not deleted before update

(cherry picked from commit 2dd73009323ec9a86fe44d6e6725026db448ba57)
include "fallen" authors in the current board, but don't include them in the ranking
no need to capture
it's only a chain if it has more than two items in it
anchor the regexp at both ends
generate yearly boards
link each yearly board to the next and previous years
pulse entry for 2014-08-25
no need to repeat "the whole year"