irclogs.php: comma-delimited list of years archive

More compact screen layout per vboctor's comments in #8777.
irclogs.php: add header row
irclogs.php: added '#' prefix to channel name
irclogs.php: channel name links to irc:// url

If the channel has logs for the current year, the name links to the irc
channel on Freenode.
irclogs.php: added 'current year' column