Implement "Roles" /dev/null page

Roles page, lists ascensions grouped by NetHack roles.
It's not full reimplementation of 2013 version yet as
top scores/values are not highlighted as they were.
Move Recent/Ascended pages generation

Now it's unconditional, always generated if --dev and
--aggr is on.
Remove Dumper from roles-dev.tt
Implement /dev/null front page

This is very similar to how the previous code displayed it;
the changes are very minor. This page does not contain streaks
yet, these will be added separately.