Comment class

Again we build complex queries in PHP, because database views
aren't viable option. :-/
Migrate comment subsystem

Image now aggregates comment objects instead of ImageCatalog.
Load and display comments
Move query string concatenation to DB class
Fetching users with query builder
Fix typo in si_size()
Display human readble scores, ratings and upload counts
Purge CSS hack for IE 6
Migrate user list
One useful line of commented out debug code
Detect more URI schemes in comments
Migrate list of recent comments

MySQL is very slow to do this, because it can't efficiently
group by one column and sort by another, even if there is a
rather low limit on the result size.