added comments

added comment class and started templating it
Added tag support

Implemeted first version of tags, needs a bit of work as the mos
popular tags won't refresh yet (static calculation at startup)
added ability to page back and forward

modified the functions that returned posts to "paginate" them.
added the ability to perform text searches on blog postings, titles and
categories… needs performance improvements
fixed bug in blog_teasers with 0 result queries