Revised irc.php and IRC box in support.php
Fix layout and css for support.php page
Use relative links in support.php
irc.php: fix irc channel link description
New irclogs.php page

We now have a proper webpage for displaying the irc logs archives
instead of a direct browsing of the /irclogs directory.
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
irclogs.php: error handling for non-existing path
irclogs: added tooltip for channel link
css: fix spotlight p so text comes vertically centered
css: fix menu centering

In some cases, depending on font / browser window size, the site's menu
was not be properly centered.
Added new IRC logs archive page

See http://www.mantisbt.org/wiki/doku.php/mantisbt:irc_logs