added 404-errorpage including template and image, changed some variables
in templates and pulled parts out in new templates, fixed some bugs and
typos from previous commits

moved new events, ratings and caches HTML code generation into separate
templates and changed templates accordingly to avoid redundant code

moved generation of HTML code for RSSParser into separate smarty
template and changed involved files accordingly

moved code that generates the "new" (cache, event, rating, forum, blog,
etc.) sections into separate class to avoid redundant code
refactored and translated 404-errorpage